This is the fifth year we've done this comparo, and during that time the Kawasaki ZX-6R has always had a unique personality. It was in 2003, the inaugural year of our Supersport Shootout, that Team Green thought outside the box and presented us with a 636cc 600, and the ZX has been the power king ever since. But that distinction ends in 2007. Big K reps tell us that the cost of building a separate 599cc engine to race within the existing racing class structure no longer made good business sense, so the lusty 636 was put out to pasture.