If you get a full system (headers back) it should remove the stock cat. Not to sure if thats how the kawi is set up, but my friend has an r6 and thats how it was for him. Full system kinda pricy tho. And i've heard the $ you spend isnt worth the power you get out of it. But let me know if you do it, and how it works out for ya. Just curious, if its worth it i might have to get me some micron serpent headers. Did some readin on those and they have AWESOME hp gains.