all I race is sidewinders, I have a 5700kv in my sc10(which I coincidentally took 2'nd place in my local tracks end of season race), and a 4600kv in my b4.1. and castle stands behind their stuff, I had one esc come apart and something broke off the circuit board, sent it back to them, and they sent me a brand new one. then had another one have the negative battery wire break, sent it back to them and got another brand new one, I love castle creations!!!