There is a sweet spot for these .12 engines where the car accelerates better: it's usually around 7.0 to7.2fdr for the first gear and 4.8 to 5.0fdr for the second gear...Any gear higher or lower just causes overreving or lugging of the engine without really improving the vehicle's acceleration or top speed on a standard rc racing track, unless you have unlimited space like the lostallo massive track....