I tried my tekin 7.5 540 motor with a 13mm rotor in it today and holy cow, I'm sticking with this combo. Same lowend torque as my LRP 5.5 550 motor, more top end, and ran cooler. Hottest it got was 145 all day long and the battery was only taking back in between 1600 and 1700 mah after a 6 minute run on our indoor track.