Castle Creations motor and ESC combo recommendations for the Traxxas Rustler 4x4 Brushed and 2s, for the VXL edition.

Sidewinder w/1410-3800kv - 17 Pinion/54 spur on 2s = ~20MPH
Copperhead10 w/1412-3200kv - 17 Pinion/50 spur on 3s = ~40MPH
Mamba X w/1415-2400kv - 21 pinion/50 spur on 4s = ~50MPH

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.