on the crank shaft to get more power because it spins the accesories slowers with more ease. Right? Then as a result we have to put a different pulley on the water pump so we don't overheat. So the water pump is not being turned slower any more. We have issues with the alternator now because it is turning slower. the only things left are the AC and power steering. We dont usualy run AC while boosting and it is just idle when not used, so it is not why we get the underdrive pulley. That leaves just the power steering. Wouldn't it be easier to just replace te power steering with a larger pulley and eliminate all the rest? Certainly weight can not be that big an issue at the crank. Why do we need an underdrive pulley? What is the true bennifit? Seems redundant.