The cat doesn't do much to the sound. I had a straight through racing cat (basically a pipe) and it wasn't that loud. Then I replaced the resonator with a straight pipe and OMFG it sounded like a whaling banshi! The exhaust Resonator is the most sound absorbing part of the entire exhaust next to the muffler.

I wouldn't gut the cat though. Your gonna fail at emissions. Even if you pass the visual test you'll be running to rich. I failed 3 times with my old racing cat. I swapped it with my stock one and passed immediatly.