You lose approximately 16% of your horsepower from the crank of your engine to the rear wheels. Heres my theory, if you buy an aluminum driveshaft that is half the weight of the original do you think it would cut your loss down to 8%? This would make sense because the driveshaft is the only major thing that is located between your motor and wheels. I know some people say that buying a new driveshaft wont do anything for your horsepower. It frees up horsepower though. Let me know if this reasoning sounds correct and if not why.