I just bought a 97 Z28 with a cat back exhaust. Would i gain or loose power if i hoolowed it ot

 

Hollow what out the muffler? What do you have on there right now? You can hollow out your cat but never really heard of anyone doing this to their muffler.

 

you wont be able to tell any difference. Leave it as it is

 

it might help if there is a problem with the one's (yes there is two) that are on there now

what you should be really thinking about is long tubes with either no cats on the y pipe or high flow cats

 

A hollowed out cat probably hurts flow more than it helps.... the sudden enlargement/sudden contraction will produce a lot of turbulence. It also sounds very bad. Leave it alone. If you have to do it, remove the catalyst substrate, and put a pipe through the can, providing smooth flow.