i want to go with either a magnaflow or borla a resonator instead of the stock muffler. what size do i need to get cuz im not too sure what the stock exhaust size is. im pretty new to the cobalt scene.

 

Believe the stock exhaust is 2.5 up until the part that goes over the axel where it narrows down and then back to 2.5 . This is where the restriction in the exhaust is.

Any muffler 2.5 would work i believe.

 

Actually, the biggest restriction in the stock catback is at the inlet of the resonator. It's only 2 1/16" i.d., so replacing the resonator is a good first step to a high flow catback.

 

i was pushing 250whp/250wtq on the noodle header, 3" cti catted DP(blown out cat), 3" x 30" cherry bomb muffler(in place of the stock resonator), the stock axle back(with the stock muffler) and a crap tune

so yes change out header, dp and cat back...as the exhaust moves through the pipes it cools and condenses a bit so having a small muffler will hurt you less than a small header/dp...from what i been told

 

Was just talking about the catback part. DP is a huge restriction as well

 

So was I. The resonator is part of the catback man

The inlet of the stock resonator (catback) is 2 1/16" i.d.

I should have clarified my statement better.

 

so definitely go with like a 2.5" inlet and outlet?

 

2.5" cat back is perfect...3" header collector and dp are a good idea too

 

Not to thread jack or anything but I was wondering if it is well worth the money/gains to buy the 2.5 stainless mandrel pipes from mandrel exhaust systems website and then do my own choice of resonator/muffler? I guess this would be a good thing for the OP to know as well.

 

This.

 

there shouldnt really be any gains from doing it that way other than you have the choice of what muff, res, and flange(s) you want to run, it could easily run you more expensive doing it that way too though...how well it flows/sounds all depends on what parts you use

 

So doing the header/dp is really the best and replacing resonator(for sound) and over the axel and muffler. Sounds good to me haha.