I have a zx6r and let me tell you i can smoke a cbrr 600. My bike is completly stock nuthing fancy done. I have raced bigger bikes than myself on many occasion. My most impressive i guess was racing a pretty strong modified gsxr 1000 03 model. He could only get me by about a half a bike lengh in the 1/4 so im very very happy with the results seeing the 400 ci disadvantage im at. The zx-6r i have can keep up with and even out run some r1´s just depends on the rider .