Castle Creations motor and ESC combo recommendations for the Traxxas E-Revo "1/10th" scale.

Mamba Monster 2 w/1515-2200kv - Stock gearing (15/54) on 6s = ~45MPH
Monster X w/1515-2200kv - 18 pinion/54 spur on 6s = ~55MPH

Note: All speed estimates are with stock tire diameter, high quality batteries and appropriately sized battery connectors.
Always monitor ESC, motor and battery temperatures on new setups or when changing gearing or batteries.