I just installed the MRP 300cc upgrade kit. I never got to ride it before the install, so I can't say how much improvement it is. I haven't taken it past 45mph either. I'm brand new to 2 wheels, and both me and the new motor are in "break in mode". It's begging me to open up and fly. lol. Gotta build up some nerve first... those wind gusts are spooky even at 45mph!