3.9 real long gearing slower accelerating
4.1 gearing a bit shorter slightly quicker accelerating
4.3 shorter gearing quicker accelerating
4.3 you would be pulling 3rd gear around most pd street tracks (near standard power)where a 3.9 would'nt have the legs for 3rd unless you were flat out on long track like mondello carrying plenty of speed..
Higher up you get to a ie 4.9 you get the quicker acceleration and higher gear you can pull
Dunno if that make sense to ya ha
