10 or 12 is more than adequate. when taking into account the coil resistance of each brake magnet and typical runs, drop is acceptable. with the factory skimpy wiring on our and a prodigy, full brake on the prodigy wouldn't lock up the brakes on dry pavement. After going to 12g and soldering the connections, including bypassing the typical side to side wiring in the axle, 6 or 7 will lock up the brakes at 60mph on dry pavement.