Ok i was talking to this guy last night that has a 10sec grand national with a big block. He said that " If you just chage the muffler it will be the same as the cat back. I want to no if i just change the muffler will i gain as much power as a cat back.

 

Anyone?

 

A cat-back is more than just a muffler and piping. The pipes on most cat-backs are 3" a few are 3.5" and 4", stock is 2.75"
Most people go with 3" cat-backs