just bought a 21.5 to try out in my f1 car. running a novak currently and its pretty fast. just started gearing down a bit to see if i could get it to go faster and i almost have that sweet spot gearing on the motor. ill test out the trackstar and see if i can find that sweet spot also so i can compare. i also have the trackstar warmer and really like it. not much use for carpet as its still to wet and rainy and cold here in nw washington. but i cant wait to hit the asphalt. hopefully the new motor will serve me well.