[captain harlock]

I suggest that you go with the HV system since you will truly see a noticeable increase in time and speed over the brushed one. In the future you might want to get a more advanced power plant for your truck which needs to be modified to some extinct in order to tolerate the higher powers of the new power plant. When that time comes this place is the right one to turn to. About the gearing of the HV, just use the same spur and pinion that came with the stock Maxx and you might be able to add a teeth or so if you want a little more of speed.