i have a 86 trans am 305 tpi. i was looking at the exhaust the other day (doing a flexplate swap) and noticed the exhaust is 2 1/2 y pipe , and a 3" cat back with 2 1/2 duals out (no headers though). all of it is aluminized. is this aftermarket or did some come like this stock? my 85 z (carb) had a way punier exhaust . the car isnt on the road as of yet (just got it not too long ago) and i was curious before i started upgrading.

 

It should be 2 3/4" not a full 3" system.