Castle Creations motor and ESC combo recommendations for the Redcat Vigilante:

Cobra 5 / Mamba XLX2 w/1721-1260kv - 23 pinion/48 spur on 8s = ~50MPH

Note: Requires optional motor mount to fit 23T pinion. Vitavon makes on that works well. Stock motor mount is limited to ~20T max.

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.