Well, I have all Losi Products, I.e., 3 LST2's, XXL, Muggy, 2 Eight T's, and all sorts of other stuff. But what HPI doesn't tell you is that when the built the HPI Hellfire, they stole Losi's LST/LST2/Muggy Front and Rear Diff assembly and designed there truck around it including the bulkhead design (the bulkheads are not exact, put pretty darn close. So the gearing possibilities are endless for the Hellfire. The truck has a lot of potential on the race track as I scream by most other racers with a stock HPI K4.6 (which is my Practice Motor). I run an LRP .28 in it any other time. My gearing is stock for now, but I can keep up with a radared at 56mph. Plus, My Hellfire is Completely Graphite as I have a Graphite Addiction. Graphite Parts include Shock Towers, Brakes, Steering Plate, Diff Brace, Full Upper Deck. I have not weighed the truck, but I'm sure its at least a pound lighter than stock.