Start off, with a IFI Transmission kit. Turn down the centers of the internal gears (not shown in this picture, but there are pictures from other teams who have done it here). Next, take the output sprocket, and turn that down. Turn it down A LOT. The end result, is a sprocket thats .4 lbs lighter, and combined with the cutouts on the internal sprockets, knocking a pound off EACH transmission.
According to our machining mentor, the sprocket will still be fine. He’s a machinist at the local nuclear power plant, so we generally try to trust him. My jaw dropped when I saw these done.