I bought this kit for my razor mx500 and powered it via 48v 20ah lithium ion battery pack and I'm pleased. The motor is very quiet, has decent torque and great top speed. Install was a bit of a hassle as I had to cut off the base plate and countersink 2 of the 3 screws holding the motor together so the motor would fit in the rear swing arm and then i had to reuse my old 11 tooth t25 sprocket but it wasn't too hard to do. One thing I've found is the throttle response is super sensitive which makes slow cruising a bit tricky but overall I have no complaints!