When installing UR lite weight pulleys you see significant performance advantages. The first advantage is a reduction in the engines rotating weight, which the engine has to overcome every time you hit the gas. This reduction in rotating weight means your engine spools up faster giving better acceleration. The second advantage is under driving, which simply means turning the engine accessories at a slower speed so they don’t rob more engine power then they really need. We adjust the amount of under drive for each engine to maximize the power gained without hurting accessory efficiency. Both of these advantages translate directly into better gas mileage due to the engines lighter rotating weight and the accessories reduced power draw equals less fuel used by the engine everytime you hit the gas.