High Performance Catalytic Converter??

I have a C5 and want to put high performance catalytic converters on it... Has anyone done this? Who makes the best one? And how much louder will it make the car? and Has anybody played with putting a aftermarket "X" or "H" pipe in the factory exhaust system or swapped out the factory "H" pipe for a aftermarket "X" or "H"? and how does it change the sound? Does it sound louder? Does it stop the Cackling or popping on Deceleration? Thanks for your Help!

What year/engine?

1997 Corvette Ls1 Thanks For Your Help