I tried searching....
Anyways this weekend I'm getting my exhaust installed. It is a vibrant header/downpipe ( unfortunately temperately cat-less due to the postal service breaking the cat loose) with a custom cat-back..Magnaflow round muffler 6inch diameter and 14 inches long as the resonator and a Magnaflow oval 8 inches wide 14 inches long muffler.

I've been wondering how much power it will really add.Will it be comparable to STG 2? Anyone know about how much WHP full exhaust adds(no random guesses please).With what I'm adding it shouldn't be much louder than stock right?

 

quite louder than stock.... and you won't gain as much as you did from stage 2

i would say between 7-15 whp

 

You will not get stage 2 numbers.

 

https://www.cobaltss.net/forums/2-0l-lsj-performance-tech-47/cti-ss-header-cat-back-installed-full-3-a-20692/

 

ZZP, and JBP give good estimates for gains.

 

i have the vibrant header/dp with the cat and i noticed an nice difference then i put on a corsa exhaust and gained a few more ponies. you will def see a nice gain if you wanna compete with stgs 2 tho get a custom tune, trust me its the best money you will spend. i can beat stock evos and sti's now and lightly modded srt4's i raced 1 gms2 cobalt w/ an exhaust and put about a car on him 0-100

 

That sounds right but closer to 15. It's a good head/dp.

I'm calling it. If you think you can beat stock sti's and evos with exhaust and a tune and nothing else then you are living in denial; they weren't racing or didn't know how to shift. The sti and evo are sub 5 second cars and don't have wheel hop.

 

maybe you should read some more he said he has a exhaust and stage 2 with a tune