on an 00gt. a flowmaster catback+prochamber, or a slp catted x+catback. the reason i ask is one has cats, the other obviously doesnt. would they be ablout equal?
Thats difficult to say. There going to be within a few horse power of each other. I'de say if you're wanting to choose between the two, choose the one setup that sounds the best to your taste and choose the one setup of the best quality.
Persoally, I have the Mac prochamber and I love it. I doubt I'de have anything else. It's up to you though and its up to what you like.