I'm running the 1515/1.5D on 4s and I'm sure I can safely gear it up to 50-55mph right now, its pretty darn strong and powerful as well. The thing is running ICE cold. I'm quite sure it has much to do with running LPR tires and the Hyperion G3 VX packs too.
I have been thinking about getting Knucklehead towers from UE. Light, strong and higly adjustable. I just got rid of a set of RPM tower with a Emaxx roller I sold...
