Just wondering if the stock SS/SC exhaust is mandrel bent? I'm going to replace the rear 2 1/4" section and put a Magnaflow muffler on it. I might just get regular bent for the rear for now. Will it make that big of a difference?

 

Yes the stock Exhaust in mandrel bent, if you get a crush bent exhaust you really will not see any gains, for best gains you want mandrel bent.

 

Well I put on a Magnaflow Muffler (Race Series) and upgraded the pipe too 2 1/2 instead of the 2 1/4 rear section....Made a BIG difference. The stock muffler is heavy and the most resticted piece in the exhaust system. The resonator is ok too leave its hollow....I thought there is no way I am spending 400-800 dollars on a catback when the piping is the same 2 1/2 as stock. Just replace the rear section and buy a Magnaflow or good muffler you will be happy. Colin

 

that highlighted statement is very true.

 

Exactly!
I measured the stock system and it's indeed 2.5" until the last bend. why spend a bunch of money on a shiny duplicate of the stock setup with a different muffler!
I would suggest buying a single SS mandrel U bend to cut and section to duplicate the final section and choose your own muffler. Might actually take 2 U bends. A bit of fab involved, but WAY cheaper than an after market cat back.

How loud is your car Colin? Did you use one of the long mufflers?
I am in the process of putting Magnaflow race muffs on my Nova....at 3.5", they are just a bit too big for the Cobalt!

Ron

 

Wait and save, the cat-backs are worth the money!

 

Actually they aren't. I have spoken to a lot of GM techs and guys from the performance division. They all agree with th eprevious statements. Remove just the section that is restrictive ( the muffler) put on a flowmaster or magnaflow muffler. If you want put on a magnaflow cat converter. You will see the same hp and db gains.