jeff, forget what these guys are telling you... start with a certain pinion then start your lap counter. id say start with 18 t pinion and stock spur gear. then start going down in gearing and see if your lap times start getting faster or slower. head in the direction of fast laps and stop once you've passed the threshold of gains then stop there. motor temp, timing, and everything else can come secondary after this. if your getting huge top spedd at the end of strait then your over geared. you should be hitting top speed at 25% of largest strait then having p[lenty of time to slow down to make controlled turn. then all the smaller turns should be in relation to that.