I've gone for a Speed Passion 3000kV system with a Turnigy 5000mAh 2S 20-30c lipo. I really don't want to go any faster than this,but the great thing is,that even with a 27T pinion attatched,the motor barely even warms up. Temp increase even after a 10 min run is just 10 degrees,and gives you about 32mph.
