If you will race at any ROAR sanctioned events, I believe 4S is max battery allowed, but for regular club racing, not uncommon to see 1400KV motors on 6S to improve efficiency and reduce temps. I have grown to rely on HobbyWing electronics and have only ran my buggies on 4S. I would consider investing in a parallel board too, might come in handy to charge 2 (or more) packs at the same time.