So currently on my Z28 Im running a dual exhaust but im not 100% if its true duals. I havent been under the car yet. All I know is that it has flowmasters, NO cats and smells like S***!!! The smell has been really getting to me lately, the inside of my car smells straight up like exhaust fumes. Both of my exhaust pipes are running side-by-side along the passenger side of the car. Does this mean it isnt a true dual setup? But basically my question is, whats the BEST flowing/sounding cat I could add to my car and wouldnt make it smell so bad? I also want to add an electric cutout before the car for when I feel like pissing people off lol

Guessing what you have isn't productive. Go take a look.

JamesC

Id love to but I dont have a garage and theres about a foot of snow on the ground and another 1-2 ft on its way...so I wont know for a few days lol

Lets just say I DO have a true dual setup...will I need 2 cats & 2 cutouts?
If its not a true dual setup how would that work out?

-Look under your car right behind the wheel if you see a y pipe or two pipes going into one then it's not true dual. Just from what you said I don't think it is.
--If this car is passed emissions or has been driven on the road then it has to have a cat, My money is there is a cat--
-If you are getting a smell while driving it is mostlikly the cat is clogged up and the smell is the crud in side burning. Don't drive it till you get it fixed cause it may caught fire.
- Any new cat is going to stop the smell. flowing can be debated but over all there is going to impede the flow of exhaust gas. While i maybe wrong the cat doesn't do anything for sound that is your muffler and tips. You can get a performance cat from summit just plug in your info in there site. This should be the once you need to look at.
--If you really don't have a cat then your pipe is clogged up because to not having a cat--
You need to take it to a exhaust shop and get them to clean it out then get a cat.
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Now about cut outs. In some states you can't have them at all on a street car. In others you can have them but they must be behind the cat and closed on roads. Most track people put them as close to the start of the exhaust as possible, I know some people that have done this to there road cars. Why they get away with it is because there smart there not looking to show off or piss people off. Pissing people off with cut outs is stupid and great for having cops pull you over. You can get as many as three tickets for cut outs and that with them being after the cat, having them before can get you in more crap. I know ricers around here that have gotten ticket for this show off crap. heck If the cop even thinks you have done it he can write you up for electric once cause he can say you closed them after he pulled you over. You don't want anyone to know you have them except the people you can trust.

Actually I was just thinking. Instead of putting a hole in my wallet and getting a new cat/exhaust cutout. Why dont I just add something like a high flow cat and just cut off the mufflers?

Does anyone run this setup on their car? How would this sound? Its a 350tpi btw incase anyone was wondering.

i ran straight pipes into the cat then dumped for a short while when doing my exhaust again and it sounded like crap. Very loud without much tone. Just wasnt a fan

Hmm...so whats your take on this? What are my options here. Im 95% sure im not running true duals. Im sure its just the Y pipe right before where the cat should be. I want the car kind of loud like it is now but I just cant take the smell anymore.

cats should help the smell but it sounds like you are too rich to begin with and the car just needs tuned up.

I'm not sure why alot of people say their exhaust smells bad, because i have run my exhaust at idle both rich as hell and lean, but never had a stink to it. Sure you can smell some exhaust but you can smell exhaust on all cars. It doesnt hurt the eyes like alot of people say and is not unbearable in smell.

First verify what you actually have and then we can go from there. If its just a single exhaust with no cat, i'd put one on to clean up the smell but it will quiet the car. Just need to run some kind of bullet style muffler to get noise back while cruisng and on the pedal.

mmmm, i love the smell of burning oil in the morning. its my cologne. I recommend mandrel bent pipes, high flow cat, i run MAGNAFLOW cat (<or i seen this cat on Rockauto.com for like 30 bucks on closeout sale, its not magnaflow.I paid extra for bolt on, so i can still remove the exhaust to drop the tank every five years or so.) Dont get a cutout if you got tpi, exhaust valves burn up. do the slip fit, and if i could replace my muff, it would be a Borla. budget maybe magna. I run flow on stock system, loud!! i love it.

Well i was at meineke today getting my oil done (too cold to do myself), and I was checking out my exhaust while it was up on the lift. My god, z28s have the weirdest exhaust setup ive ever seen!

Ok my exhaust is, 2 pipes coming from the headers leading to 2 cats(which arent there anymore), then a Y-Pipe, after the Y is a single pipe running to a flowmaster with dual outlets. I never seen anything like that before lol

So now I know what my exhaust consists of, what is everyone's opinion on a nice loud, good flowing, non smelling exhaust? Thanks

check for leaks around the pipes, gaskets blow out, donut gaskets crumble, if the tips come out the side of the car its inevitable to not have smell. id recommend this stuff that one mixes with gas and it smell like cotton candy or grape, made by Manhattan oils..find it at summitracing.com,

edit: it works for fuel injection so i removed the part when i said it didnt, my bad

http://www.summitracing.com/parts/MOC-19769-32/

Wow hahaha thats some cool stuff right there. I have a TPI though so no grape smell for me. Im pretty sure its not leaking, I checked earlier and it all looks welded up pretty good.

Its probably running too rich or has late timing so the exhaust is still burning in the headers when it comes out. Cats will clean up the smell somewhat but also make the car quiet, but the car may need alittle tuning first if its rich

What do you mean by tuning? Like computer tuning or basically getting a tune up (plugs, wires ect..)?
Because I have no knowledge on car computer tuning. Im great with computers, just not on cars lol.
I just got the oil changed today, and it doesnt smell THAT bad anymore but the smell definitely is there still.

tuning. like the mininum idle air on the Throttle body . then adjusting the Throttle Positioning sensor, then correcting the base ignition timing. old engine burn oil all the time, new engines too.

Both. Give it a good tune with fresh plugs, check timing and etc and then see if you can tell how rich or lean its running at idle. I never had a car that smelled bad at idle and i think that was due to making sure it idled in the 14-15 to 1 air fuel range, even with a big cam. My turbo motor idles rich at first startup and its not stinky at all. I'm not sure why your car is unless its burning oil

Computer tuning takes care of the fueling requirements if its too rich or too lean. If its burning oil then that may be from bad valve stem seals

Alright. Once I get a little bit more money ill have to get on that. I still need to change my plugs and wires.

Instead of adding TWO cats before the Y-Pipe, why dont I just add 1 car AFTER the Y. Just have the two pipes leading to the Y, then a cat, then to my muffler? How would this affect my ride?

Yeah you could do that. Will make it quieter and should clean up the smell but atleast its smog legal

14.7 to 1 o2 sensor reads and adjust, im just adding, peace

Ahhh im not even worried about smog tests haha. My car is inspected until September of this year, and I know people who will pass me no matter what.

Im currently checking out: http://members.optushome.com.au/iroc...st/exhaust.htm

Im loving that exhaust setup! I cant find a sound clip of that exact car but Im sure it sounds good.
Would probably cost me a small fortune though, unless I did it myself.

Well, the only thing I can really think of right now is adding a high flow cat AFTER the Y-Pipe to quiet it down for daily driving + get rid of that nasty smell, but id like my exhaust loud at certain times just messing around, so id like to get an electric exhaust cutout before the cat.
What do you think about the cutouts? Ive heard some people say they leak and all that, but other people say theyre great.

Whats your take on them? What are the chances of them leaking?
Transam85dudeman you said they burn up exhaust valves? Could you explain this a bit more?

ya, open exhaust on a tpi is kinda bad, usually from a cutout. the exhaust valves need back pressure, has to be the right amount tuned. my way of putting it in dude terms, its like playing baseball, have you ever tried swinging the bat at the ball with all your might and missed-it hurts, but when you nail the sucker its helps absorb the body force. The car has a sort of siphoning effect on the exhaust, kinda like a ram jet the Germans built in WII. people have sworn on the boards, with right exhaust system, you can actually gain more hp and torque rather than open exhaust. especially with a hooker aerochamber or borla
-i recommend a bolt on cat, heres mine, in cali (#1 strict) if you buy a cat it HAS to be made after jan 2009, to pass, they updated the cats to run cleaner. i got the big boy magflow cat. its bolt on which is perfect to unbolt the and remove the the cat back exhaust so i could drop the tank, and its stock flange. i had to get a exhaust cut-your-self gasket but forget about it.

Theres back-pressure 101 thread somewhere on the board.. anybody have a link??

I have heard that car before and its amazing. Chambered tubes are NICE mufflers. I ran one before on my L98, just single exhaust. That car in the link was supercharged I believe. Willie was his name on this board i believe. The link is no longer posted from what i see. That was back in 02 i think.

Dont worry about the cutouts causing problems, you will be fine to use them if you demand loud

Yeah I understand what you mean about the back-pressure. Correct me if im wrong but its usually just N/A cars that actually need the back-pressure in an exhaust system right? If it was turbo/supercharged, the turbo or supercharger itself would create its own back-pressure from what I was told.

It seems like a high flow cat and cutout would be the right route for me at the moment but I just wanna make sure its a good setup and all. I don't wanna go spend $200 on an electric cutout and have it leaking or messing something major up. Id get a QTP one, they seem very reputable for making them.

You really dont want any backpressure.

I thought a n/a car NEED back-pressure? Im gonna have to read up on that back-pressure thread, lol im clueless.

BTW. Any universal cat would fit right? Im gonna start looking for a good high flow to get.

The lower the pressure differential between chamber and exhaust side the better the scavenging as the gas will move high to low pressure

cutout location will be determined by the peak rpm your motor operates at for max hp. Theres a certain pipe length you want to have for best exhaust scavenging at that rpm. Place the cutouts in that length for best performance. Unfortunately i do not know that length I'd guess probably collector length of 24-28 inches? My 383 would have wanted 18" i think and it peaked at 6300 ish rpm

Yeah i think it should. What size you need? i have a pair of 3" in/out magnaflow/carsound cats i'd sell for 40 each, brand new. Its about stock size in length

Im not sure if my whole exhaust its 3" or not. I know the flowmaster is 3" but ill have to check what size the piping is before the muffler. Once I find out ill let you know because if its 3" ill definitely buy one off of you.

Stock L03 5.0 in a Jag (only mod is 1.6.1 rockers on the intake valves).... I have to use the Vette Rams horn 2 1/2 exhaust manifolds to fit my application. Gonna use a dual setup and use one of Flowmasters dual in dual out "quite" muffler. From there under the diff (solid mount IRS unit. the driveshaft and center of the rear end don't move so I am placing the muffler in the center under the driveshaft) out to the factory rear valance holes. By using the dual in dual out setup I eliminate having to buy two mufflers and was hoping to get an x-pipe effect to smooth the exhaust. My question is how far back should I place the muffler to act as a crossover? Looking to improve the low rpm range power. 2000 stall convertor to help getting this heavy car moving, daily driver, not a hot rod, I like the good mileage I get so I'll be keeping the low HP low flowing fast velocity restricted intake and heads. This is a low rpm application 0-3500. I'm using the 2 1/4 pipes to the muffler. Would There be any advantage to putting larger pipes AFTER the muffler as I have room there to do it if I want? Trying to lower the exhaust sound (tone) and thought by using the 3" pipes from the muffler it might sound deeper. Thoughts and ideas guys? Thanks for your help. I need it.

About to go measure my exhaust now to see what size my piping is.

Anyway, heres what my exhaust sounds like when its fully warmed up on a cold day (thats what the smoke is from).



I absolutely love the sound but just not the smell. Im still trying to think of some smart/affordable exhaust ideas.

Another thing. About adding a cutout/cat AFTER the Y-Pipe, wouldnt this be VERY restricting? I basically have 2 free flowing pipes that would lead into not only 1 pipe, but on that pipe is a cat and muffler. Would this be bad at all for my car/engine or would I notice a loss in some power?