I have a 3908 e-maxx that was suppose to have the mamba in it and I decided to run the Summit 775 motor because of the torque. After modifying the motor plate and a little grinding on the tranny, I now have the question of what gearing I should run. The stock 68t spur wont reach the pinion unless they make a large one. I'm also running Big Joe series 40 tires. Any help on the gearing for decent speed and torque without overheating?