Castle Creations motor and ESC combo recommendations for the Team Associated Trophy Rat:

Sidewinder w/1410-3800kv - 21 pinion / 87 spur on 2s = ~35MPH
Copperhead 10 w/1412-3200kv - 22 pinion / 87 spur on 3s = ~45MPH
Mamba X w/1415-2400kv - 23 pinion / 87 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.