i took a buddies 01 cbr 600 out the other day.. we got a 'quick acceleration kit' from vortex for it. made by vortex.
saved a buncha weight on the sprockets, gold rk chain, and dropped one tooth in the front.
1 less tooth in the front made for a much funner ride
not a fan of the riding position on those bikes.. it feels.. to comfortable for some reason? lol