on a 2000-2001 bike engine thats going into my chassis? If so what Cat? its a yamaha XJR1300 engine.

Will certainly need CAT & presumably something like Power Commander to control mixture.
I think the cheapest CATs come from the states

youll be lucky to pass any bike engine without a CAT

mk engineering do a cat for £80.00....

mk engineering link

just noticed they have updated their website