Does a higher number necessarly mean more power??? Like is a .15 faster than a .12??? Or maybe the other way around??? I wanna hook up my car with a better engine. If im gonna spend the money i want the best of the best. I dont know if it matters or not but i have a HPI nitro RS4 2 with the stock .15fe engine. I was also goin to put in a 2 speed tranny.