Well I need a cat badly. I found one on ebay that's for a 99-2000 Si, and I was wondering if it'll bolt up. Basically if everything will be fine on a 2000 GS-R with exhaust length and everything afterwards. I need a damn cat. I have to pass emissons and get tags once and for all.

I searched and all I did was lose...

 

No it will not fit

 

if you want it to fit you'll need to cut and reweld the flange(s) on the cat - the pattern for the bolts will NOT line up.