Ran the 21.5 in sportsman last night, it's insanely fast, had more than a few racers checking my car, esc settings, weight etc because it seemed 'too fast' Broke the lap and race records for 21.5 in the process. Very happy with the motor especially now it's Roar legal, have the 13.5 to try now, if the 21.5 is any indication, I may need to learn to drive again!