I have a 2006 cbr 1000rr and trying to put on a yoshimura rs5 full exhaust but having a lot of trouble with it fitting keeps having a exhaust leak any body else had this problem..

 

Where ya leakin at? Header? Midpipe? If it's at the header try using new gaskets -- if it's at a connecting point some high temp sealer should do the trick. Just use the sealer sparingly -- once it sees temp it'll swell up and come out everywhere. You can clean it up but it's a hassle.