what size jets?

ok i got a 01 400ex it was jetted when i got it ,it came with a yoshimura slip on,snorkel off,air box lid off,and k&n air filter! now it was already jetted for that and it was good! now i recently bought a new yoshimura full exhaust and i noticed it seems to want to bogg alot like it needs jetted again! now i want to run it kinda rich so what size jets should i use and what should i change?

well it depends what size is in it now... now your flowing a little more air out so you will need more fuel to compensate so just bump the main jet up a size or two, and i would also suggest throwing in a 42 pilot jet..