I know there are baffles and whatnot in my stock header/midpipe, and I figured the cat was built into it. No? I thought the 636 header/midpipe was the same arrangement, but just exits under the bike for a slip-on rather than a bolt-on like mine.What exactly do you think the '03-'04 headers do? There is no CAT, and they flow freely. THAT is why people do the swap (along with being able to use slip-on's).:coocoo Cutting the CAT on your current headers would do the same thing that those headers do.