PLEASE HELP!

Basically me and my friend have the exact bike Kawasaki ZX6R 2000-2001. I have the 2001 model, and basically he has got a HARRIS OVAL SLIP ON EXHAUST, and his fits fine. Now i purchased one aswell, but a carbon one, but i have a slight problem, the exhaust pipe on the bike is too big for the hole of the exhaust can. this is because there is about 5 inches of extended pipe that comes away from the bracket where you bolt the can onto the pipe. Can anyone tell me what this little bit of piping is for, i gathered it was jsut so if the bolts come a little bit loose not as much air would leek from the system, so i got told by a couple of my other m8s to cut that bit off? but i don't want to be cutting something off that is important. Hope this made sense people. PLEASE HELP!! I'm h8ing the sound of my bike at the moment with the standard can on!

I dont really want to cut it off, but if i have too then so be it! lol, but is there such things as a reducers, i.e. a pipe which goes from big to small?

CHUNK

Hi Chunk,
Is you bike exhaust std spec to your knowledge ?
Kawasakifreak.