ok a dude at an exhaust place said I have a 2.25" exhaust factory...
He said that I'm probably running off a 2" inch manifold or something and with my resonater already cut off and w/ my aftermarket muffler that it wouldn't breathe any better with a 3" all the way back without getting a new Header and wouldn't add to my performance but just make it sound deeper.... Input?
Thanks

 

well, he's somewhat right.

the factory pipe narrows at the rear axle. now, bang for the buck, the header/dp will def give you more power for the dollar.

now, that said, you'll prolly need to have the ECM at least adjusted to deal with the 2nd o2 sensor (these cars seem overly sensitive). so, figure the cost + $100 to have it tweeked

 

no resonator and an aftermarket muffler?
dear god that has to sound like a chainsaw.


3 inch is to big for the power your making IMO.

 

I have to say when i put on my header and dp before changing out the catback, there was a HUGE difference. I then put on a 3" exhaust and it helped, but it was loud as ****, so i put back on the stock downpipe. After that i didn't feel as much punch, dp>catback. I'm sure header is the same way, i've had two different headers, and i have to say they are the **** and should be put on before any catback changes if you're really looking for performance.

 

good man. +1 rep

 

haha it does.. WAAAAAAAAAAAAAAAAAAAHH wwaaAAAAHHHH. it dont bother me tho. so, Header + dp and a ecm tweak? who would tweak my ECM?

 

get 2.5

 

2.75" is the ideal unless you're going for 300hp.

 

It would probably depend whos near your area. ZZP performance actually sells a replacement ECM which would probably have the required adjustments for the o2 sensor codes, and extra performance modification. I opted to buy an Aeroforce Interceptor Gauge, which can delete codes while installed, so i just delete my p0140 code every time it pops up. I've tried multiple different setups with or without a CEL eliminator and/or catalytic converter and it always seems to throw a code, our cars are sensitive.

 

3 inch is reserved for the 300hp mark. If your not at the 300hp mark please remove it promptly and adjust your exhaust system accordingly.

Thank you.

 

big pipe diameter not always good loose power and tq's. go for 2.5" pipe.

 

The factory manifold is the worst. It's completely chocked and the factory downpipe is 2" at it's best. As stated by LopsidedJester, you do benefit more from headers/downpipe over the exhaust. Im running stage 3 on Factoy Exhaust, and it runs perfectly fine. I only upgraded the header and downpipe. So yeah a 3" exhaust on a factory header/downpipe won't benefit power, it will just turn up the volume full blast!!!

 

wait a min. has anyone here made it to 300hp

 

Yes a few.

 

ROFL

*looks around*

 

A few people have I think.

 

Key words right there lol

 

it was a legitimate question. ive heard a few talk about it but not seen the big post on how to get there. thats all

 

I know it was a legitimate question and I was laughing cause...well...

you know

 

268whp = 300 crank horsepower

 

^^^yea....or maybe he meant to the wheels

 

theres more than we think.

any of the guys running 2.5/2.6 with full boltons, meth and a good tune are knocking on 300.
even most of the guys with boltons + stage 2 + spray are also probably very close

 

ya i was asking at the wheels...

 

Eventually there will be a 300whp cobalt club, or even 400whp =P soon im sure....

 

o i know there will be but there were a few people on this thread talking about not doing a 3.0 exhust unless you have 300hp ... i was just wondering how many of these guys have 300hp and can attest to the 2.5 not getting you to 300