[RC-Monster Mike]

Increased torque is not optional with high voltage brushless motors! It will happen no matter what. The xl3100 will run a bit hot at that voltage and will be too powerful to handle in my opinion. As I said, the xl2400 on 22.2 volts will achieve your speed desires with the proper gearing, but will run cooler. The xl2000 would be my choice. ASgain, this will provide plenty of speed/power, but will have better runtimes and cooler operation vs. the xl3100. I doubt you will see 50 mph on a racetrack anyways (40mph if your lucky).