Just check out Radio Control Nitro mag for May 2005 . A fusion with a sirio 21 and the optional gearing hit 88 mph radar confirmed. Also a Fusion with the stock motor in it and the optional gearing hit 75 mph in RC Car Action Feb 2003 Issue radar confirmed. If you don't believe me just check it out for your self. I am tired of people misrepresenting. The Ct4s is the fastest out of the box un modified 1/10 scale racer but it is not the fastest modified! The Fusion 21 is! This has been verified in Rc Car Action Feb 2003 issue & Radio Control Nitro mags May 2005 issue.