I use the 2650/mmm and run it on 3s with a 17t pinion. It is a bit slower than the other buggies on the straight, but has all the power I need out of the turns and up the face of the jumps. I like the controllability with 3s over 4s (when I run 4s I run a 16t pinion) on my local track (8th Wonder). After 12 minutes main, my motor is under 160 degrees.