Need to buy a pair of cats. I'd like to improve the flow over stock cats, since I'm spending the money, and doing the work. "The work" involves welding up a new dual cat Y pipe that will be 2.25" instead of the stock ~1.sump'n to 2".

Looking at options, you got several options ranging from OEM, CARB approved ("California") replacements to cats that look like bullet style mufflers, labelled as "race cats". What's the diff? What is a non "Cali" cat? Does it not reduce emissions (as much?) or is it simply not CARB cert'd? What determines determines cat "flow", be it "hi" or Po'"? Would simply getting a larger in/out sized cat qualify as, or functionally be high(er) flow? Or does the fontal area of the monolith define/limit the flow?

What's the diff between "metallic" cats and "ceramic" cats, functionally?

I read, years ago that there was some development in cat tech that improved flow while also improving emissions reduction and was a significant contributor to enabling the C5 Z06 to go from 385 hp, up to 405 hp. Does anyone know what that tech was and is that standard fair in all/any new cat? I.e. a moot point?

"Cali" Carb approved
Cheapy-cheap....
RACE!!!


Thanks for reading.

 

In my non-professional opinion, the CARB approved Magnaflow is the only one of those that will do much for emissions and power output. The other two that you posted are likely an exhaust restriction due to the very small bodies. Unless the monolith brick or whatever is in them is not the typical fine mesh design. And if it's not the typical design, I'd guess they are not very effective and there's not much point in having them other than to pass a visual inspection.

But again, that's my non-professional opinion. I've only seen inside one of those type mini-cats a couple times (don't know what manufacturer) and they looked very restrictive.

 

lets start here.
why do you need to buy cats?

 

Does Utah use CA emissions laws and require CARB-approved parts? Or are you actually in CA?

CARB cats supposedly have more precious metals to reduce emissions more effectively, which might explain why they're quite a bit more expensive than 49-state cats. But whether or not that's still true today or was ever true, the processes of tooling for special products and getting such approvals probably add more to the price than typical production costs. When I lived there, they only checked to see if a cat is there (the sniffer will tell if it's working), but now "they say" they will also check to see if it's CARB-approved, if it doesn't look original.

Density of the substrate will affect flow. Metallic construction is different than ceramic construction. Metallic cats tend to be more durable, less dense and flow better than ceramic cats, but those qualities can come at the expense of effectiveness. Ceramic tends to be denser, more effective and cheaper, all of which makes them great for general use, but they're more likely to crack, break or disintegrate from excessive heat and abuse. Race cats tend to be metallic, and while some work very efficiently, others may not pass by the numbers, but they all help.

The size of the core has to be able to handle the flow, otherwise it will restrict flow; that's why their bodies are larger than the pipes. You wouldn't want a small diameter cat with a tight, small core for a strong engine, unless it's for a dual exhaust with two cats splitting the load, so to speak, just like you wouldn't use small exhaust pipes for a strong engine, unless they're dual. Depending on the density/cell count, the core should be large enough for the gases to enter and pass through without getting backed up at the entrance.

I'm not familiar with the testing on the C5 you mentioned, but what you're describing sounds like ACAT catalytic converters. Their metallic cores are different than typical metallic cores, and they make similar claims. They offer CARB compliant cats too. I don't know if their statements are true, so it would be best to look into it for yourself, rather than take the word of people who've probably never used or tested them.

Cats are required by federal law, as we all know. Whether people believe in law and order, or they just think they're above the law, laws still apply to them, so go without at your own risk. Even if a state or an area within a state doesn't inspect or test emissions, and people can probably get away without cats, cats are still required, so people will be subject to a violation if caught without them. Kind of like insurance, you might never need it, but you'll be happy you have it if such a time ever comes.

If people think cats don't work, or they love to complain about emissions laws, then they should move to an area without emissions testing, where they're driving behind cars that probably don't have cats, and their eyes are watering and nose is burning, they're trying hold their breath, and they realize, this is what it must've been like before emissions laws, when ALL cars were polluting like that, then people might appreciate cleaner exhausts. Fortunately, even in such areas, most people have and love their newer cars and technology, so gross polluters aren't the norm. But still, just because some people might not mind the smell of their own farts, they probably don't like being behind someone and having to smell theirs.

 

Because Red and his boy Hick Neckerson, removed the dual cat exhaust, welded up a nice “T” pipe, no cat(s), cut the rear O2 harnesses (on the vehicle side, rather than unplugging them), ran the "T" into a single 3”, no muff and out a right side, side pipe. Sounded like ****, obnoxious, smells like azz, probably makes less power….DUMB.

I'd like to put it back to stock…or better than stock, no smells, have reasonable sound levels with some quality tone....you know....not suck?

So maybe some ’02 or newer, Z06 Cats?

 

There's no emissions testing in the county I live, and we have the cleanest air in the USA. I'm not telling anyone to remove their CAT, but I get tired of the virtue-signaling from some people. There are so few cars as old as these on the road, they're not having any substantial impact on the environment. In fact most thirdgen owners don't even drive them daily...

 

Some counties in UT require emissions testing, where I live, does not.
Pretty sure Maine, Wyoming and Hawaii have the cleanest air in the US....but either way, I want cats on my car(s).

 

I don't think there's necessarily any physical or mechanical difference between one w CARB EO # and 49-state. More, it's $$$$EXPENSIVE$$$$ to CA certify something, and it has to be done for EACH INDIVIDUAL part (not a "blanket" kind of thing, as in, I'll send you a sample and I'll promise that every other similar part I make is like that one) for EACH INDIVIDUAL application (not "this part meets some spec", butt rather "this part on a 91 Z28 w 350 TPI" which excludes "this part on a 90 Z28 305 TBI" and so on) which means it's a GINORMOUS PITA. Frankly I can't the least bit blame a mfr of aftermarket parts for not putting themselves through that.

Really, it comes down to what fits your car. Most modern cats, you can look RIGHT THROUGH them, as in, you could read a newspaper looking through the honeycomb. Most of em, I doubt you could measure more than a HP or 2 different between a cat and a straight pipe with the same size fittings. So, if your exhaust would accommodate, say, a 12" body that's 16" end-to-end, w 2½" ends, in a straight line, slip-fit, 5" dia max, then that's all you really need to know.

The catalyst itself is metallic. Various rare precious metals that make it worth people's time and risk of going to jail, to get up under vehicles in parking lots w a Jeffrey Dahmer saw to steal em. "Ceramic" is a bit of a red herring; "ceramic" nowadays refers to a class of metal compounds, which once it's a compound it's no longer "metallic" as such, butt many of which may include some of those rare metals. Not really something you'd make, say, a coffee cup out of. Sometimes it's little more than a buzzword. I wouldn't put too much stock in it.

I'd think that virtually ANYTHING you could buy today would outflow anything stock from 35 yrs ago. I'd also bet that the fittings on the ends can be at least as restrictive, if not more so, than the catalyst itself.

 

Well said, I agree with all of this. Every time I get stuck behind a stank *** car I think about what it must have been like on the highway in the 60s. Unpleasant I'm sure!

 

Not cleaner than my county.
And why doesn't CA have the cleanest air in the USA?? They have the most strict emissions laws in the country.
My comment was not anti-CAT. Just pointing out that a few thirdgen owners without CATs are not destroying the planet...

 

Because of the weather and atmospheric conditions. Even with their regulations, the air gets so thick out there sometimes, it's all butt unbreatheable. I recall one time in about late March or early April in the early 00s when I had to drive from N SD Co to Pasadena, so I went up the 15 and then west on the 10; by the time I got to Pomona the air was so thick and brown I could hardly even read the signs anymore. At that time of the year the air comes in off the ocean and gets stuck, can't get past the mountains, so whatever is in it just accumulates; you end up with like a month of car, industrial, etc. emissions just hanging there. Another time, went up to Mt Palomar, and from up there, you could see LA in the distance: looked like a giant mud puddle. Could hardly even see the buildings. It's just as bad up north sometimes, esp around Santa Clara, San Jose, Mt View, etc., at the south end of the Bay.

That's a PERFECT description of LA air sometimes; except, imagine poisonous farts, as in, can cause bodily damage from the concentration of acids and whatnot. The whole city smells JUST LIKE that. Smells like the stockyards out in Corona and Norco except worse. Trust me, it's not about "virtue signalling" AT ALL.

Once you see the problem with your own eyes, setting up laws to handle it makes AHELLUVALOT MORE sense. Laws are a funny thing though: they apply to EVERYBODY. They have to. Wouldn't exactly be fair to make ones that showed favoritism, now would it.

 

Actually, laws DON'T apply to everyone, even though they're supposed to.
The evidence of that is everywhere.
Again, I am not against CATS or emission controls in general. Modern cars emit nearly zero pollutants, and vastly outnumber cars from 40+ years ago...

 

The "supposed to" part is the most important. Just because some rich, influential, popular, well-placed, or whatever else kind of people, get a free pass, or weasel one out of the courts by legal sleight-of-hand or sheer exhaustion, doesn't mean that we shouldn't at least TRY to write ones that DO apply equally, and then ... at least TRY to apply them equally.

 

No disagreement there...

 

I am on this band wagon as well. 1 of my N10 CAT's is rattling. Probably the outer 1 as they all do.
I can gut both CAT's. I can replace both. I can put in straight pipes. I definitely don't want the stink.
I called Magnaflow 2 years ago. No such thing as 'high flow' by Magnaflow.

I have seen 200 cell CAT's. Supposed to flow better than 400, or whatever else is out there.
CARB CAT's. None CARB CAT's. Nothing is legal in NY except OEM.

The guy above talking about rear o2 sensors is on crack. We have OBD1, not 2.

I haven't done anything yet, because the car runs fine with the rattling CAT.

 

Care to share your county so we can compare it vs the CA counties that drag CA as a whole down in ranking? It is simple math on why areas of CA have "bad" air. Population density.

I am all for antique cars getting a pass on emissions testing and I am all for less regulations. Nobody here is claiming thirdgens are destroying the planet. You are arguing against an invisible target.

FWIW my car STINKS even running closed loop and is incredibly loud. That was fine 15 years ago when I was 18 years old. Now I regularly contemplate throwing CATs on it to tame it. My permanent tinnitus sure would appreciate it, sucks getting old.

 

This about sums it up. I like QUIET!!!! Quiet Quiet Quiet!!!!!!!!!!!
Original owner 1989, figure out how old I am now !

Quiet Quiet Quiet!!!!!!!!!!!
I have an SLP CAT back. and my stock N10's. 1 of which has failed.

 

El Paso County. We got rid of emission testing in 2006.

I'm not arguing against an "invisible target". People here get chastised all the time for removing their CATs or other archaic emission controls. I just wanted to comment on that even though it is slightly off the main topic...

 

https://www.lung.org/getmedia/5d8035...e-Air-2025.pdf

Table 3b lists Colorado Springs as 9th for Year-Round Particle Pollution. Hardly the "cleanest in the country". Honolulu, Hawaii does in fact rank #1 tied with Casper, Wyoming.

You are going to make me sound like an old grump by saying this when I really am not....especially considering my own car doesn't have CATs...

People might get "chastised" here for it, but it is for reasons unrelated to air pollution. The "chastising" almost always is because of the direct negative effects it causes to the people in the immediate area. IE in traffic. In 2026 there really isn't a valid reason to not have CATs other than wanting to be obnoxiously loud. We have factory built NA engines making serious power with all the current emissions requirements.

 

I'm in agreement with that. Sure, with the pellet-bed cats of the early 70s, there was a YYYUUUUUUUUUUJJJJJJJJJJJJJJE performance hit; butt modern honeycomb ones have almost no negative effect at all.

Last few times I've been out to CS, admittedly it's been maybe 7 - 8 yrs or so, the air was visibly dirty. You could see it driving in. You can REALLY see it around Denver flying in, which I did every few months at least, for many years; yerbasic grey-brown haze. All the towns on the range front there have a similar situation to California: frequent temperature inversions, that trap all that crap.

I just don't see where there should be any objection to having cats on a car. Yanking em off is about in the same class of things as pouring your used motor oil out in your back yard, or letting your toilet flush off your back porch. Sure, it might be your yard, butt all that CRAP doesn't stay there. It fluffs itself out to infect everybody else. IMO it's all in the same class of things as throwing your fast-food garbage out on the highway. Decent people don't litter the world around them like that, with ANY kind of their waste.

 

The only "dirty air" you were seeing is dust, not pollution from internal,combustion engines.
And you don't have to convince me that CATs are a good idea. Once again, my comments were not "anti-CAT" or anti-pollution controls...

 

I've discovered that the information varies depending on what website you check. But yeah, we are in the top 10 of cleanest air counties. I have no doubt that Hawaii is cleaner. It's an island in the Pacific ocean. No way any of the eastern states in the U.S. have cleaner air on a regular basis than where I live.

My 53 year-old F*ord never had CATs. You can smell it at idle if you stand behind it, but not in the car while cruising down the road. It is also properly tuned, so it's not making eyes burn . Again, I was not advocating for removing CATs from cars that originally had them...

 

But....Maine does. And, that's an eastern state, last I checked.

The entire premise of your original comment was massively flawed....even if your facts were actually correct! Your initial claim:

I live in Park City, in Summit county. There are no emissions inspections at all. Other people live in Salt Lake City ~15 minutes away,, in Salt Lake County....where they are required to have emissions inspections, annually. By your logic, Salt Lake air should be cleaner than the air in Park City....right? It's not though...in fact, the air in SLC is terrible, so bad people are advised to stay inside, many winter days and advised to "drive less". So by your logic, this is."Proof that CAT's don't work!!" Right? Wrong.

I'm at 7100' elevation, in a county with ~43,000 residents. SL county is at 4200' elevation, between two mountain ranges (a valley) and has a population of >2,000,000. Salt lake has 2mil+ people, running gas stoves, furnaces, AC, a coal power plant, inversion....all contributing to and trapping pollution in a valley. I live above all of that, and COULD proudly proclaim the superiority of our air, over Salt Lake's air...even if we, in Summit County, can run amok w/no CAT's.

I live at 7100' elevation in the mountains, I get water from a well. If I dump my **** down stream of my house, and claim, "I've got the cleanest water in the country!!".... is that proof that my **** don't stink, b/c my water's good? Not to the people down stream of me!

As you can see, the premise that your clean air is a function of CAT use or not, is folly. Even if your air actually were the "cleanest air in the USA!"...it's not b/c the county removed the requirement for emissions testing and/or CAT's.

Anyway, you've made your point; You're not "against cats".



Now, back on topic.....What is this, referring to?...

 

My very basic understanding is it is a measure of "filtering" being done by the CAT. Kind of like micron for filters. So a 200 cell CAT will not be as restrictive as a 400 cell CAT because it is designed to allow more through/flow better. The question would be what exactly is being described as a cell. In old honeycomb style CATs I could see it having individual cells, so that is just a count of them. But with new designs I am unsure of their internal design relation to "cells".

 

Apparently I have not "made my point" because most of what you said is nonsense. Maine does not have cleaner air, but more importantly, we are in the TOP TEN. Do you have any idea how many cities and counties there are in the USA? We are in the top 10 and have no emissions testing (because it's unnecessary).
THAT is my point; that a few owners of old cars with removed emission controls have not and will not destroy the environment. Nothing to have a melt-down over.
Of course it's better to have a car that doesn't have stinky exhaust...

 

Are we arguing over who has cleaner air? Al Gore is so proud.

 

Painfully obvious you didn't even bother to look at the published study I provided...

Table 3b lists Bangor, Maine at #5 while Colorado Springs at #9.
Table 4b lists Hancock County Maine at #5 while El Paso County doesn't even make the list of Top 25. Notably not a single county in Colorado is on the list.
In the state tables page 62 El Paso is graded with an F for High Ozone Days and a C for High Particle Pollution Days.

It is increasingly difficult to understand your position when you triple down on 100% false information to try and justify any point being made.

 

MAN....The point that I made, blew right by you. You didn't even catch a hint of it.

And no one was having a 'melt down", except you, maybe. Oh well. As you were.

 

Thanks. That makes sense. Appreciate the input.

 

A catalytic converter (abbreviated as "cat", not "CAT") isn't a "filter" at all. A "filter" would trap and retain something, which a cat does not do.

They are a surface made of various precious metals, onto which free oxygen deposits itself due to atomic-level attraction, as it passes over. Combustible substances in the exhaust stream (carbon monoxide, complex hydrocarbons such as improperly burned gasoline, carbon soot particles, etc.) pass over all that, and the catalyst metals release the oxygen while encouraging it to react with the undesirables. The end products of perfect combustion of hydrocarbons whether within the engine or in the cat are water and carbon dioxide; while CO2 has its own issues, at least it's not poisonous, brown, sooty, etc. The water part of the exhaust passes on through the cat unchanged. The catalyst itself does not directly participate in the reaction, and thus is not "consumed", or at least, only very slowly. In a honeycomb cat, the catalyst material is kinda like many many long thin hexagonal tubes, in line with the exhaust flow, with their surface exposed over their entire length, that the exhaust gases pass through. You can literally hold up the catalyst and look through it in the direction the exhaust flows, which usually, is right straight through from one end to the other. You can see right clear through it. Obviously if there are enough tubes, the only "restriction" they cause is by way of the friction of the gases passing by them, meaning that if there are enough of them, their "restriction" can be made equal to or less than that of the rest of the exhaust pipes. Older cats typically required either that the engine run so lean that there was excess oxygen in the exhaust, which has all sorts of bad effects, or that oxygen be pumped into the cat continuously; the AIR (air injection reaction) system aka "smog pump" and all that stuff, originally designed to burn off the undesirables by brute force, was re-purposed for this. Newer engines with EFI accomplish it by continuously varying the mixture so that for some part of the time it's lean (too much oxygen, leaving some left over in the exhaust stream part of the time), butt most of the time the mixture is correct for best engine operation; by this method, which appears in diagnostic codes as "cross counts", extra oxygen such as from the AIR system is not generally required.

The "200" & "400" kind of numbers refer to how many cells there are in some unit area, like per sq in or something, I don't know what unit exactly. Again obviously, a "400" can be made to have as low restriction as a "200" if the total catalyst area is larger, butt this would make the OD of the cat larger and of course more expensive, so there's only just so far you can go with that in the real world.

 

You're funny. Even if Maine is cleaner than Colorado Springs (which is in EL PASO COUNTY), we're still in the TOP TEN for clean air. One site says number 6; another says 9. WHO CARES? My point is no less valid regarding classic cars that have their cats removed. They're not destroying the planet.

But yeah, you really "showed Me", didn't you??
SMH...

 

I can assure you I wasn't melting down about anything.
I also was not arguing your point...

 

But....you didn't "get it"....at all. You proved that by saying this:

Did you read the water analogy?
In one ear.....

As you were, my man.

 

"There's no emissions testing in the county I live, and we have the cleanest air in the USA."

"Not cleaner than my county."

"But yeah, we are in the top 10 of cleanest air counties. I have no doubt that Hawaii is cleaner. It's an island in the Pacific ocean. No way any of the eastern states in the U.S. have cleaner air on a regular basis than where I live."

"Maine does not have cleaner air, but more importantly, we are in the TOP TEN. Do you have any idea how many cities and counties there are in the USA? We are in the top 10 and have no emissions testing (because it's unnecessary).
THAT is my point;"

You asked who cares. The answer is anybody who cares about the information they are taking in being factual. I have a tick against false information being spread, especially continually after being shown the information isn't true.

My problem is using false information as your way to reason your point. You don't have the cleanest air in the USA. You aren't the cleanest county in the USA. You aren't in the Top 10 counties for clean air. Maine does have cleaner air. Some eastern states do indeed have cleaner air on a regular basis.

What is hilarious about this whole discourse is we actually agree that a minority of old cars are negligible in the grand scheme of emissions output of the country as a whole.

 

Incidentally, the description of cat operation I posted above, is for the oxidation (rear) section. Most modern cats have 2 sections, one for reduction and one for oxidation. Both use precious-metal catalysts, just, different combinations of metals, chosen to promote their specific reactions. Oxidation obviously is the same thing as "burning", which is what carbon-containing pollutants need done to them to render them as harmless as practical. Reduction is the opposite chemical process, i.e. splitting oxygen atoms out of molecules that contain it. The reduction section is designed to work on nitrogen oxides, which are MAJOR contributors to acid, poisonous, corrosive, unhealthy, etc. LA type smog. Specifically, the cat splits them back up into nitrogen which is what almost 80% of air is anyway, and oxygen. It also splits up ozone, an oxygen molecule with 3 atoms as opposed to the more familiar 2 atoms, into the diatomic form, since while ozone is extremely important and beneficial in the stratosphere, down here at Earth's surface, it's mostly a very bad thing. Exhaust gases pass through that part first, then through the part I talked about earlier. The oxygen liberated by the reduction section can be used in oxidation, although the amount of it produced is only very small.

 

I would also note, that the reason so many places are "getting rid of emissions testing", is NOT because their air is so clean, or that they've quit caring about their air, or that they're being "fair" to classic car owners, or ANY SUCH thing. It's because modern engine control systems are capable of monitoring their own performance in that area. So, consuming public funds on emissions testing in this era of automatic "Tax BAD! Gummint BAD!" CRAP from the numskulls that have hijacked more traditional "conservative" principles and thereby hamstrung ALL government functions at every level, is no longer a high enough priority, in the grand scheme, to be continued. After all, at the state or local level (below where, say, military or foreign matters are concerned), PRIORITY in public spending must go to police, fire, education, road maintenance, and other such things. If 99%, or however many it actually is, of all vehicles on the road can test themselves, then spending precious tax dollars on mandated emissions testing, which ultimately only enforce compliance with existing laws by the other 1% (see comments above about "laws applying to all"), is no longer important enough to dedicate those dollars to. Those among the 1% (or however few they are) of vehicles old enough that they CAN'T police themselves, i.e. pre OBD2, who are unwilling to comply with the laws that supposedly apply to EVERYONE, essentially get a free pass (again, see above about "weasel out").

 

Well put. In 2026 it is getting increasingly rare to even see 90s vehicles let alone 80s. The piece of pie for "dirty" emissions vehicles will continue to get smaller and smaller. The vast majority of vehicles on the road self govern themselves with regard to emissions. It was different 20 years ago when that piece of pie was much larger. I am sure there is data available to these areas with testing that shows the number of "failing" tests are very small. If say 95+% of all vehicles you test pass, why waste those tax dollars?

 

What's hilarious is that it's apparently a "win" for you if we are only in the top 10 for clean air and not at number one or two. The top 10 out of HOW MANY cities/counties in the USA???
Nothing you have said has disproven my point which was that with no emissions testing whete I live, there has been no negative affect on our air quality...

 

Having been to Colorado Springs, I find it LAUGHABLE that you'd make this claim. It's BOGUS on the face of it and makes you look less than ... yeah. You should be ashamed of yourself. I seriously doubt that El Paso County is even in the top 10 cleanest-air counties in the state of Colorado, let alone the ENTIRE US. CS is a forking CITY, and counties with CITIES in them INVARIABLY have dirtier air than counties that DON'T have cities in them or at least with none nearby. Which is why Wyoming has cleaner air than most places: THERE'S NO PEOPLE in about 95% of it.

See the comments above about cars that police themselves, and since they're in the overwhelming majority these days, the need to conserve tax dollars outweighs the need to police those who are UNWILLING to follow the laws regarding air cleanliness, or those vehicles that pre-date any emissions regulations and as such are exempt from the law. There may not be any NOTICEABLE effect on your air quality, TO YOU; doesn't mean that there isn't one AT ALL.

This entire argument about El Paso County CO is logically flawed at its core and comes down to who can shout the loudest about their "right" to get away with making everybody's life around them just that little bit more miserable without suffering consequences for it.

To carry the "toilet" analogy a bit further, consider a house built before running water and flush toilets existed, which is still standing. Back in the day, people used to keep a "stool" (seat or chair of sorts) in their "chambers" (bedrooms) with a hole in the center and a ceramic or metal "pot" underneath, which they used for their necessary body functions, and then leaned out the window (or if they were wealthy enough, their servants known as "chambermaids" and such would lean out for them) and dumped it in the street. We have laws nowadays that prohibit this, and other laws ("building codes") requiring modern methods (flush toilets, which a man named Crapper made considerable improvements to, and whose name thus passed into slang in an uncomplimentary way), although no doubt many of these words will be familiar still. In fact, these laws even apply to existing houses (no "grandfathering" allowed for the "chamber pot" system), whereas emissions laws are more generous in that area. Have you ever been to Venice, where many of the oldest buildings still discharge their sewage straight into the canals such that THE FIRST THING that hits you stepping off of a plane or train or ship there is the stench of POOP, giving rise to such expressions as "full of canal water"? Should a person living in such an old house (go visit London or Paris or Amsterdam sometime to see where there are LOTS of such houses still serving as residences) still handle personal sanitation this way? Would you like it if you lived on the 2nd floor of an apartment building and your neighbor on the 3rd floor directly above you, even though this house is newer and was originally equipped with flush toilets, decided that the law was inconvenient, and followed this same ancient custom? What if the neighbor felt he could get away with doing this instead of keeping his plumbing in working order, and simply counted on lack of enforcement? OF COURSE NOT. Which is kinda the whole point of the majority of "laws" in the first place; most of them, at their core, are nothing more or less than "The Golden Rule", except that since there are some among us who seem incapable of following that Rule in all their ways, need careful explanation delineation and coercion. Emissions laws are in that class of things. Butt, as mentioned previously, enforcement is where "laws" usually fail.

 

So if I get it, a modern 3-way cat and tuning it out would give me semi-emission compliance, functional cats and elimate the AIR junk.

 

I think it's hilarious that YOU still think that it matters to the position that you took that started off this entire de-rail!

 

Overall, generally, probably, if you can get enough extra oxygen into it somehow, I think, butt I'm no expert. Not sure how good of a job TBI does at that. Semi compliance at least though.

 

Actually, I was driving from New Hampshire into Maine today and there was a sign that said "we have the cleanest air in the country". There was a sign right after that that says " because we all use high flow cats on our f bodies".

Ive heard of people having good luck w modern cats on numerous muscle cars. These are guys w dual exhausts w 60s/70s cars. Obviously no testing data but they don't stink! My TA used to stink. After dyno tuning it got much better. My bronco was the same when i got it, outside idling was nauseating. I changed the target AFR a little and it made a massive difference. In both of these situations the engines were clearly too rich. I would imagine if i just put cats on the smell would be better but the longevity of the cats would have been severely negatively effected.

 

My position is 100% valid. We did away with emissions testing BECAUSE it wasn't necessary due to the FACT that our air is clean. It WAS NOT to "give classic car owners a break". Talking about how Hawaii. Wyoming, and supposedly Maine have even cleaner air is irrelevant to my original point...

 

Even Gretta Thumberg isn't this annoyed.....

 

^LOL^. Well.....at least I got some good info before the TL-DE-rail!

• 

 

Lol! I do believe this would be the perfect note to end this thread on.

 

NO.

The reason why your community, along with hundreds of others around the country, have discontinued emissions testing, has already been covered.

TL, claiming that your air is the "cleanest" in the US, or really even ANYWHERE CLOSE to it, is ludicrous. I'VE BEEN THERE enough times to KNOW BETTER myself. Continuing to insist on this fantasy makes you look like a liar, a fool, or at best, merely misinformed. You're better than that, as you've shown in other discussions on this forum. While it's COMPLETELY OK to dislike "virtue signalling" and other obnoxious behavior of that sort, MAKING UP random "statistics", or completely misinterpreting real ones, is another matter entirely.

We all get it, you don't like catalytic converters. OK fine. That's entirely your right. I'm not sure why you don't, butt of course, you don't "owe" me explaining why you don't, and I don't really expect you to, and it's OK regardless of whether you can, or choose to, explain it, or not. You can like or not like whatever you want for whatever reason, or for no reason at all even. OTOH, arguing stupidly about it, by inventing absurd claims that can't be backed up by real-world data and in fact FLY IN THE FACE of the data that's available, let alone what you or anyone else can see with your or their own eyes, isn't the best way in the world to make your point. You're better off just letting the man who wants to put a cat back onto his car, for whatever his reasons are, do what he wants; maybe tell him you don't like cats and you don't think it's necessary; butt DON'T LIE in the process. It demeans you. You know better. You should be ashamed of yourself for that.

 

 

Exactly! It was just like that but w more trees!


i think another issue w cats on out cars the distance from the engine the cat is mounted. Modern cars usually mount a cat as close to the engine as possible. Our cars thats kind of difficult. Its amazing how fast the exhaust gas temp drops as you move away from the source of heat. My powerstroke has 5 egt probes along the exhaust. Unless im on it, the temps fall fast down the exhust line. If im on it, its a different story.