Does anybody know the difference in weight from the c/f chassis to the aluminum chassis? That, I think, is the big difference. I neglected to weigh the chassis before I put the car together, but I think the weight savings with the c/f chassis is substantial. I also think the big ticket is Aluminum chassis+Shorty Pack = weight savings. The problem I'm having is that I can't seem to get the same punch throughout the full 6 min. What are the absolute best of the best Shorty packs?