I have an 07 cobalt SS/SC, i plan on getting a stage 5 kit from intense racing that contains a ported supercharger, a 2.5"pulley and 60lb injectors. I am also getting a CAI, duel pass intercooler, and heatexchanger but i don't know what exhaust size i would benefit from the most. Should i get a 2.5" or 3"? also, should i have a cat converter or not?

 

3" exhaust.


And don't stay on the canned tune. Get your car dyno tuned.

 

Get tuned instantly.

 

Same as above, Tuned and 3".

3.

3 okay? lol Preferably Vibrant... awesomeness.

 

what about the cat converter, should i have one or not?

 

at least a high flow cat.

 

okay well I assumed when you said exhaust you meant catback. if you mean headers as well then go with a full vibrant setup... they do a nice header/dp/high flow cat setup that is bar none, as well as a bomb ass catback.

 

Why do you say this? My 3" catless DP mated to my cat-back sounds pretty and preforms pretty dang good for being 3".

 

let me ask you this, do you have to do anything special to run a downpipe with not cat? like custom tune it or what not?

 

Not really , but it's nice to have the 2nd o2 sensor shut off so you don't have to look at the service light from the cat removal.

 

As of right now I do not. I am going to have a tuner delete my 02 code at the midwest meet in 2 weeks though. However the car runs great as is.

 

with that setup, get a 3 inch.