Oic whoopsy i thought that was the only thing you found. Dont know much about the traxxas blast but if your going to use a 540 motor i would go off the motor that came with it or something simialar such as the mabuchi 7520. At maximum efficiency it pulls 13 amps. Other than that i would email traxxas. Are you trying to put a larger motor in? Or lower turn?

http://www.alphalanding.com/rc-track/rs_540rhsh.pdf