well guys ive just finished putting on my stock gt front and sides and left the streetfire back on which DOES flow with the 00-02 gt kit nicely and im thinking of redoing my exhaust setup. Right now i have 2.25" downpipe back with gutted cat and i want to upgrade to 2.5" downpipe back basically to see if it will increase my horsepower and track times but have seen abunch of posts on here about how 2.5 is too big and then some say 2.5 is perfect for the gm s/c application.
I have noticed that when i gutted my cat out i lost a noticable amount of low end and the car got louder of course. so would you think i'd lose more low end with going 2.5" downpipe back with a high flow cat or what because like i said alotta guys on here have said they use 2.5" and love it but then others say different so what you guys think once again on the whole gm s/c exhaust deal? Ive been told before that since i am running nitrous as well as boost 2.5 should be perfect but i just dont wanna do this and lose power and track times, the whole 2.25" exhaust deal might be robbing me of some track times and power, i just dont know so wanted to get some comments before i actually did the whole thing.
also, i see alot of guys i know with cobalt ss/sc using 2.5" catbacks and seeings nice gains so this is another reason why i think i should make this change, my buddy has amazing top end, he said he noticed his top end being real good after the upgrade on his exhaust. i beat him at the track on low end though but once he hits about 70 his speedo just sucks down fast and hes running 13.8's to my 13.9's.
im using 2.25 and i love it, i honestly dont think it will make a huge difference, i mean there will be a diff, but not worth the money in my oppinion
i loved my set up when i had the s/c.
isuzuperformance header, 45inch 2.5inch thrush glasspack, 2.25 RK single cat back over the axle(exhuast hanger off a 4 door 2k j body to keep the exhuast tucked up tight ), and a 2.5inch dynomax superturbo muffler, and a stock looking turn down.
i tried alot of set ups in my day, and so far this one sounds the best i think.
Team GREEN
after thinking about this over the years, my opinion is to try to run a full 2.5 all the way from the header collector back. in my case, the collector on my pacesetter was 2.25, so instead of messing with it, i just ran 2.25 and i'm fine w/ it.
-----------------------------------------------------------------------
-----------------------------------------------------------------------
- Sold my beloved J in April 2010 -
Yes you would benefit from a 2.5" exhaust from the header back. More air and more fuel equal more exhaust gasses. If 2.25" works well for a N/A setup, and you're pushing more air in and out of the engine with a supercharger, the larger piping will work well for your application. Also, not a good idea to gut the cat. All that stagnant air will cause a loss in velocity. Having a cat also helps keep the exhaust hot, which maintains velocity. So adding a high flow cat to the 2.5" exhaust will also benefit your setup.
_________________________________________
450WHP Turbo Ecotec swap in the works...
