Buy an XO-1 if you want to go 100 MPH. This vehicle was never designed to do this. You'll get far too much downforce from the rear wing, and that will lift the front taking away your steering. We know this because we put a 21 and 23 pinion on a HPI Vorza on 6s and preceded to destroy it. It was hauling ass, but the front lifted and it did a blowover at a speed that had to be around 100. Having no front wing to keep the front planted will likely result your vehicle's demise if you attempt this.