cronsformula350

I should record a video of my iroc with my flowmaster, my exhaust gargles and screams more than alot of other cars around my town, and better than alot of clips and such from these sites, with flowmaster's, not to mention it's louder.

D's89IROCZ

Well after reading all this . I am still gonig with SLP ...stainless ....fat flanges ...and 1 3/4 ( so I don't need to upgrade one day .....)

But to all them posts about the smaller y pipe . It makes me wonder if..... it was made that way ...to be married to an SLP exaust for the car . I am reading about wave tuneing and , scavanging right now . I don't have it all understood yet . but it seems to me that you want to have the right parts to go together <----- bigger is not always better . So with that in mind ..... I went with the better material ...... and bigger diameter primaries ( to accomidate the more hp later in life )


now ....here is my question .....with the bigger primaries on the SLP's ....does this smaller collector and y pipe diameter .....create that desired effect that I just refered too ?

D's89IROCZ

wlll they hook right up to the SLP y-pipe?

Jaded

I need a new exhaust, Mines about ready to fall out. So I'm lookin for a new one. My mechanic wants 200 to replace it with a new stock exhaust. Any good exhausts for not too much more then that? Lookin for 86 Firebird exhausts.

cronsformula350

I have a high flow factory 3" y pipe off my 89 formula 350 in great shape, and the stock one off my 87 iroc-z thats brand new, I'd be up for selling either of them if your interested.

xlwhellraiser

iTrader: (1)

How 'bout some cheaper headers. 600bucks is outrageous, I installed Flowmaster for my 79 bird for only 120 bucks, street legal at that. Maybe because I orderd them from Jcwhitney, I dont know.

Kevin91Z

iTrader: (1)

Factory stock I-Pipe on an L98 engine is 2.75". There are no 3" factory stock I-pipes, no matter who tells you or what you think is on your car.

There is a difference between street legal and smog legal. You arent getting any brand new smog legal headers that are cheap. Its just the nature of the business. The government charges the aftermarket companies a huge sum of money to test the parts and make sure they are smog legal. So the companies charge a high price for their products to make up for it.

xlwhellraiser

iTrader: (1)

Well, I live in CO and I passed emmissions no prob. Actually my numbers were better than the previous ones( 79 bird). Go figure. But if that is the nature of the bussines, than what is the cheapest headers that I can put on 89 LO3, that can pass emissions. Also if I put headers do they still have to go out in one pipe or is dual a better way to go????

iggy1991

I installed the hooker 2055s on my LO3 Camaro. I'm pretty happy with them. I did have to put some bigger washers with the header to Y-pipe flange bolts cause the heads of the bolts were a little small. It was also a PITA to get the passager side one in. I had to feed it from underneath the car. But with all that crap over there its a pain to do anything. Also if your gonna get these make sure you install new plugs and get new plug wires with ALL angled boots. I also had to modify a wrench to fit in and tightin the plugs cause the header tubes run right infront of the plugs.

cronsformula350

Kevin, my 89 Formula 350, has certain 1LE options, proven by its rpo codes, which I had verified at a pontiac dealer(Bert Adams) in my area. This car had an original 3" y pipe, from the factory, and many of the mechanics there in shop also verified this. One of them, that was there when the cars were new, also verified this for me, in telling me that, since he has been there since 81, when my formula was new, many came into the shop with the same 3" pieces, and they were factory. Many things are in many of these cars that aren't supposed to have them. But like the cars of the earlier days, alot of things slipped out through the factory that weren't supposed "to be" not that it matters to me if you believe this or not, but this is how it is.

cannondale125

what about the ceramic coated edelbrock T.E.S. headers, i havent heard anything good or bad...anybody care to comment

cronsformula350

I have the tes nickel chrome plated shorties, and there y and I'm am very pleased with the quality. I am sure the Ceramic quality would be great too.

Kevin91Z

iTrader: (1)

Ceramic coated Edelbrock headers are still the same bad design regular Edelbrock headers, just with a spiffy coating on them.

Crons, I'd like to test your data in the history/restoration forum. My dad has been an auto mechanic in the SoCal area for over 40 years, and did many exhaust swaps on thirdgens when they were new. Not once did he find a factory 3" diameter exhaust pipe. They were all 2.75" or 2.25". My car came with certain 1LE options too, namely everything but the brakes and aluminum driveshaft. Its called the G92 package. And its i-pipe was 2.75". I guess GM shipped special cars to your area of the country.

cronsformula350

What's this then?

cronsformula350

Here is my Iroc's factory y pipe, notice the pipe had to be enlarged to fit the cat, my formulas was the same size as a 3" cat, 3" outlet y pipe.

I bolted on my iroc headers and got into the thirteens, I started with the headers bolted on from a 15.1 to a tune of 13.8, while still spinning the Nitto drag radials horribly, my iroc would turn a 13.5 or better with suspension work, but Its up for sale now. Edelbrocks also have a better collector design than the hookers headmans, Jba's.

cronsformula350

Here is my Iroc's factory y pipe, notice the pipe had to be enlarged to fit the cat, my formulas was the same size as a 3" cat, 3" outlet y pipe.

I bolted on my iroc headers and got into the thirteens, I started with the headers, and my own custom exhaust bolted on, and went from a 15.1 to a tune of 13.8 at 100mph with only a 1.9 60ft, while still spinning the Nitto drag radials horribly. My iroc would turn a 13.5 or better with suspension work, but Its up for sale now. Edelbrocks also have a better collector design than the hookers headmans, Jba's.

Kevin91Z

iTrader: (1)

That looks like a regular run-of-the-mill 2.75" i-pipe to me. Do you have a micrometer you can use? Or at least take a pic with a ruler across an opening. That pic shows nothing.

And if you had to enlarge the i-pipe to fit the cat, that means the pipe is smaller than the cat. What kind of cat do you have on there, a 3.25"? I doubt it.

cronsformula350

notice how I said my Iroc's y pipe had to be enlarged.

My formulas isn't the average run of the mill y pipe, The cat I had on my formula was enlarged to fit the y pipe, aftermarket cat was installed.

Its ok you don't have to believe it I have what I have, I don't need to keep telling you what it is, and argue with you about what I have like a couple of little kids, no biggie, I'll sell it to someone, and they'll enjoy having it.

Just like you say edelbrock headers are horrible but once they were on my car with my exhaust I increased my mph by 10, but they are garbage headers, uh huh, sure they are. I'll stand by my garbage made in usa edelbrocks any day of the week.

Kevin91Z

iTrader: (1)

Ok, now you're going over the top. You increased your MPH in what by 10? I hope you're not talking about your 1/4 mile times. There is no way you're gaining 10 MPH in the 1/4 mile just by bolting on a set of headers and exhaust. Top speed, I can believe, but not 1/4 mile.

iggy1991

yeah I don't agree with that either. I installed the hooker 2055s with an open cat and my LO3 didn't gain any mph but got down the track .3 quicker

cronsformula350

Well, maybe you can't tune very well, but I have people that were there witnessing me, and timeslips to prove it. I bolted on my headers and my exhaust, 3" bullet muffler, and a dump before the axle, and went from a 15.1(89mph) first run, to a 13.9(99.9Mph) the same day, 11 runs later. All I adjusted was timing(34* total advance) and fuel pressure(47psi); ON the original motor and trans with 146,000 on it. The car slips so bad I never made one pass without slipping out of the whole, and on the 2nd and 3rd shifts, with nitto drag radials. The car has the power to run a 13.5, but with stock suspension, its hard to hook.

Bolting on headers and exhaust requires mild tuning, to see a full benefit, and fuel pressure and timing adjustments are just that.

Avenger007

Hmmm...this is difficult. Im looking for a more solid answer and not finding one. I want a 3" flowmaster to hook to a 3" cat so now I need headers. I want to remove my AIR system and just get non-AIR headers so what is a good set thats 1 3/4 and wont take much modification (if any) to install. I heard scraping problems with the 2055s, definitly something I want to avoid. Also, SLPs setup is waay pricing IMO so whats tha way to go?

custom88camaro

I also think it is stupid to use 2.5 in pipe for y pipe. I bought one not knowing how small it was. I took a 3" mandrel bend 90, and welded it in place of the 2.5. It seems to work, but I think my real restriction is those 1 5/8 primaries.

Kevin91Z

iTrader: (1)

SLP makes the only shorty-style 1 3/4" headers. Your other choice is long tubes from Hooker. Everything else is 1 5/8".

In regards to a 2.5" y-pipe, I hope you're talking about the exit point where they merge together, and not the pipes themselves. The pipes are only carrying exhaust from four cylinders each. 2.5" is fine for that. The exit or merge point should be 3" yes, or whatever size your i-pipe is.

custom88camaro

I have investigated the slp's, and they look like the way to go, but they are bending people over! I think they are a tad pricey, but I would eventually like to have a set. I am using the hedman shorties (68470) and the y pipe (17970, I think). I could not believe that the merge point was only 2.5. My factory I or Y, whatever you want to call it was just under 3". I called hedman to ask what they were thinking, and the guy said "We do that so you have better bottom end power." I suppose it does make some sense, but not much. I cut the section that was 2.5 off right where the two header pipes come together and welded on my own 3" mandrel bend 90*. I have no cat to worry about so it was pretty easy.

vortec77

Hey anyone here Install a set of edelbrock nickel chrome plated shorty headers? I was installing the Y-pipe and noticed that I have to get a reducer from 3inch to 2.5 where the y-pipe meets the cat. Anyone else have this problem? I have an 86 T/A converting from carbed 305 to TPI 350. I had an edelbrock header system on the 305 similar to the one I have now and I dont remember having this problem. It just bolted right up to the cat. The only difference from the header system I have now to the one I had then is that the new system is nickel chrome plated. I called summit because thats where i bought the headers from and they say it should fit without a prob. They say im gonna have to get a reducer to make it fit, anyone else have this happen to them? Thanks,

iggy1991

The 2.25in cat will hurt your perfomance. Get a direct fit 3in catco cat so you can use the stock Ipipe and muffler untill you get a good catback.

custom88camaro

No, but when I bought my hedman y pipe (which is 2.5") it came with an adaptor/bushing to go up to the 3" cat. I think that one of the reasons they made the Y pipe have such a small outlet is for your cat setup. Edelbrock seems to have a better idea with making a big outlet, (for the larger cat), but they should send a bushing/reducer to work with the small cat. My old I pipe and cat setup came off of an 86 TPI IROC. Well officially, I do not have a cat anymore because my car is an "off road" car.

vortec77

ok thanks for the response.

BrandenCali

Face the facts.. If your looking for performance gains.. Pay attention to the design of the header.. There are many types out there.. And most of the time a cheap or bad design will not gain much..


And the Rare 3" y or what ever.. That was a lil off page.. But your in reference to.. What's the best exhaust.. Keep it at that.. We don't need to learn any rare 3rdgen's they put 3" y pipes on.. You don't want to reveal the diameter anyway.. So let's keep that talk on another subject.. Where there maybe a person that will partake interest in.. As to find out if there was so vehicle made..

jimmy_mac

Update, I ended up cutting the hedman y-pipe back to where the two 2.25 inch pipes meet and just ran 2 mandrel bent 2.25 pipes down the same route as the I-pipe used to go. The difference was amazing. Hedman is full of ****e with this 2.5 inch pipe crap and talking about better for low end power. I even noticed I can cruise at highway speeds with less throttle. My mileage went up also. I just wish I have before and after time slips. Unfortunently my before slip with the 2.5 inch single pipe was with my old heads and now I have vortects. In any case I went from 98mph trap speeds to 105 mph. I'm sure the vortecs are responsible for at least 3 of those mph.

Bottom line, a 2.5 inch single pipe if a travesty. Whoever decided to run that product at hedman should be fired and hedman should be forced to pay everybody's costs for converting it to a 3 inch or running duals like I did.

custom88camaro

nascar2496

iTrader: (2)

hey guys, im kinda new at this whole header thing and would like to ask of your opinions: I have a 83 z, 350 edelbrock carb and rpm intake, and a cam. I want to put 3 inch exhaust from the headers back. my question is what the hell do i look for? ive looked at heddman, hooker, slp and im just confused at the moment. i dont need any smog stuff and would like shorties. any suggestions? and as far as the rest of the exhaust is gonna be mandrel bent 3 inch with flowmaster super 40 muffler and 3 or 3.5 outs, if that helps. thanks

Camaro_nut

All this talk about 3" exhaust. Anyone ever get a Mufflex
3.5" or 4" exhaust? Maybe even a custom 3.5"? I have
the SLP 1 3/4" cerama-coated headers w/ Y pipe going
to a 3" Random Technology cat. to a 3.5" Mufflex exhaust
w/dual exits. Traxion had the 1 3/4" SLPs with the SLP
Y pipe. He was doing 11s in the 1/4 with that setup.

SLP 1 3/4" headers and SLP Y pipes are proven to 550hp.
You don't need a 3" Y pipe unless you intend to make over
500-600+ flywheel hp.

You DO need, however a 3.5" exhaust for over 300 RWHP
and a 4" exhaust for over 350+ RWHP. You will gain power
going from 3" to 3.5"/4" pipes. Either that or go 3"
dual exhaust with LT headers for that amount of power.

25THRSS

Having a 3.5 or 4 inch catback will do nothing if you still have a 3 inch y pipe. An exhaust is only as good as it's smallest point. I still have a 3 inch catback on my LS1, which makes nearly 700 flywheel hp with nitrous, but plan on switching to a 3.5 inch catback to match my 3.5" PPC y pipe soon.

Camaro_nut

People here using a 3.5" or 4" cat back have GAINED hp at the
rear wheels with only 300-400 flywheel hp. That was over there
previous 3" cat back too. I am one of them. I am only using
the 2.5" SLP Y pipe. Marc 85Z28 said he gained power from
switching from a 3" cat back to a 4". He is also using the
SLP 1 3/4" headers, but made a 3" y pipe. But still, that's
a 3" Y pipe going to a 4" system. He also gained power
going from Edelbrock 1 5/8" headers to SLP 1 3/4".

And if exhaust is only as good at it's smallest point, then
why have 1 3/4" headers and a 3" cat back? why not have
1 3/4" from motor back?

Maybe each system would work differently to each
application. There's so many different engine combos,
that some people may be using the wrong parts and
not even know it. I would think that a stock 350 TPI
would benefit using 1 3/4" headers with the SLP Y pipe.
And just a high flow 3 " cat back. But if over 300hp a lot
of people say that you can benefit using a 3.5" or 4"
system. I know that it's NOT overkill using 1 3/4" headers
on a 350, especially mine. GM highly recommended 1 3/4"
specifically for my motor.

25THRSS

This makes no sense at all. There are more things to consider like velocity and scavenging, but it make no sense at all to install a Y pipe like the SLP, which has two 2.25 inch pipes that "Y" into a single 3 inch pipe, then install a 4 inch catback. You still won't be able to flow more than that 3 inch section allows. Also, if you have an engine that needs a 4 inch system, the 2.25 inch collectors and piping for the y pipe will also become a major restriction in the system, thus making the entire pre cat exhaust a rectriction. It's pretty pointless IMO to install a 4 inch catback unless you have the rest of the exhaust system to match.

T.D.K

Figured I'd pose this question, I have a choice to make and I'm not sure what to do.

I've got a 92 RS 305 TBI (L03) and I'm converting it to TPI this summer. But.. before that I need to replace the exaust, as it is currently falling off :/

Currently the car has the single CAT setup on it. I'm wondering, is it worth it to convert to the dual cat setup? And if not I'm having troubles finding a single performance CAT that has 3" inlet / outlet, does such a thing exist?

Thanks for the help.

Avenger007

Catco and carsound both make 3" in/out catalysts for pretty cheap. There are a few others out there too like dynomax i think and slp has some. Check out summit.

T.D.K

Ya I just found a bunch on Summit that are 3"

Still wondering about switching from single to dual CAT

Kevin91Z

iTrader: (1)

GM rated the setup at ten more horsepower. Plus, 4 cylinders flowing thru 1 cat is better than 8 cylinders, right? Just make sure your exhaust guy uses mandrel bent pipe, and uses a true y-design to join them after the cats, and not a t-design like factory.

T.D.K

Good point. I have another concern though. With the 305 will I loose any off the line power due to lack of back preasure with a 3" exaust?

I'm goint to eventually put a supercharger on it after the TPI conversion but it may be a while because of the $$$ issue.

So in the mean time will a big exaust like this have any adverse effect on my day to day street driving?

fst2qtrmile

when i did my exhaust, i bolted up hedman headers w/ a 3" collector. Then brought the rest to my buddy. He welded in an )2 provision for my o2 sensor and then reduced the 3" collector to 2.5". Then he built me the Y-Pipe. All manderal bent stainless steel piping. The way he did it, it flows so smooth out of he engine. The Y-pipe runs 2.5" off the headers, then collects into a 3" collector - no cat. Then runs 3" to the flowmaster system. The TPI setups create torque at low rpms and when u run 3" all the way back or even true dual, you will actually loose that torque. Thats why he ran 2.5" then collected into 3". Also, he didnt want to do 3" because of ground clearance. I will get a pic up soon - this Y-pipe is nice. Well just thought i would add my 2 cents.

T.D.K

Thanks for the good info.

Ok taking into account all that I'm learning here.

How does using Edelbrock headers into CatCo dual cat setup (2.5" inlet/outlet) and 3" the rest of the way back into a flowmaster.

I figure that sounds like it would get the job done. Yes/No?

fst2qtrmile

if i were you, i would use your piping from header to cat as 2.5 for clearnce cababilties. I wouldnt even use cats, but if you must, go with 3" because cats will creat enough back pressure as it is - so go with 3" cats. I would run 2.5 headers to cat, then run 3" from cat - making the cats 3"

Kevin91Z

iTrader: (1)

Dont worry about backpressure, as he said having the cat on there will take care of that.

Edelbrock headers are the worst in my opinion.

Lastly, your questions belong in their own topic, not in the FAQ topic. If you have any more questions, please start a new thread.

vortec77

Why do you think edelbrocks are so bad?

T.D.K

Moved / continued my topic in a new thread.

HERE

jconrad

Ok, so the 2055's have the 1-5/8" primaries just like the 2460's right? And the 2460's do not have AIR tubes. (I pass smog without any of that hooked up anyways). But the main difference is with the collectors.
The 2055's have 2-1/2" ball flange (stock type) collectors?
The 2460's have 3" 3 bolt header flanges with gaskets?
I would like to maybe have a muffler shop make me up a 3.5 or 4" y pipe to use with a Mufflex cat-back.
Or would the gains be similar with the 2055's 3" y-pipe?
Now, where do you find a 3.5 or 4" cat?

Camaro_nut

I don't think you will find a 3.5" or 4 " cat specifically
made for our cars. I don't think there's a 3.5" or 4"
cat. If you don't see them sold on Summit or Jeg's,
try Ebay. If not there, forget it and have a pipe made
instead. Just forget about passing emissions. Good
luck on finding the cat.