i was wondering if there would be a difference between a punched out stock cat vs a after market test pipe? i realized that inside the cat is pretty wide and the exhaust is only 2 1/2 inches. the test pipe is 2 1/2 all the way through. would there be a difference or am i ok with the punched out cat?

 

Gutted out cats still cause a lot of turbulence, a testpipe will be more efficient.

 

moving....