1. Driven aluminum rear sprocket
So far so good. I went up two on the rear and stock in front, per Brian’s recommendation for first time change. For a 16 ZX10R, I needed an impact drill to remove countershaft sprocket nut and nuts on the rear sprocket. Kawasaki made them super tight. I’m 230lb and pretty strong. My tire spoon looks like a “u” from being wedged in back wheel and attempted by hand. Removing by hand should be fine after you’ve re-installed nuts.