Hi, i have a 07 ss sc and since several month i have a gmpp catback waiting in my garage..
The main concern : i want hp but want to keep stock or almost stock sound
has anyone ever tried or have some information about putting my stock muffler on the gmpp catback ?
Will i still gain hp ? Will the sound will be nice ?

Thanks alot for your time if you have any information that would be great

 

The GMPP catback wont give you power but it will sound better than the stock exhaust

 

HP wise.....not much. But from what I understand, most people say the GMPP exhaust is the BEST sounding exhaust for an SS/SC!!

 

a) it will give you ~9 horsepower without tuning for it, maybe a bit more if you do tune
b) it wont be MUCH louder than stock but WILL sound very very nice. def. best system to get soundwise
c) go on youtube and look up gmpp system for cobalt not too hard

 

which one do you have? Touring or Performance GMPP exhaust

 

Its the performance one , i watched about 50 video and yes its too loud for my taste i want performance without changing the sound .i dont mind a little change but nothing like the whole catback sound...
I found one video.on youtube of a redline with a catback and stock exhaust and it sound awesome ..not much louder than stock
my main concern is more performance wise is there any difference in the muffler only between stock and gmpp like flow ??
I know the gmpp should flow better ..but will you really feel it ?

 

I wanted the touring because I didnt want it to be too loud but since they didnt make it anymore got the performance. Its not really loud and sounds badass. Deff should put it on and test it out. Youll love it

 

there is a huge difference in cfm between the mufflers

 

Just go with ZZP 3 Chambered Exhaust. You won't be disappointed cause that's what I have on my car right now. It's worth it and LOVE the sound of the exhaust.

 

The stock muffler is very restrictive....

Just run the full gmpp exhaust. They sound nice.

 

Ok ill run the full catback then ,didnt know the stock one was that restrictive ,thanks for the input

 

The piping not so much, but the inlet of the resonator, and muffler are the restrictive parts.

You will enjoy the sound of the gmpp catback.

 

It cant be worse than my old mazda 3 with obx headers no cats and vibrant catback..i couldnt see nothing in my mirror when i was flooring it hehe

 

oh and idt anyone answered this... its really hard to tell a ~5-10 horsepower difference man. bit by bit as you add mods like intakes, headers, dp's, exhausts, blah blah it'll creep up with the power but it would be hard to tell unless u put a bunch of stuff on at once

only noticeable gain i've done so far was stage 2. that difference was night and day!