Serpent 966 brushless is great news but 4s liporacing?...hm i guess the ampdraw would be too high in a car like that (i already now though), i would prefer 6s and lower kv on the motor. I guess the batteries will hold up for maximum 5 minutes on 4s and 60mph. In a 1/8th onroadcar the faster it goes in the turns the better it performs, unlike for a 1/8th scale buggy there you are more gently on the throttle...