One thing you need to remember is nothing is free when it comes to forced induction. Gear Driven Superchargers do however take more power to operate than an Exhaust Driven Turbo. You are using exhaust gasses to spin a turbine which scientifically will use up power to do so, but the loss is minimal compared to a gear driven unit. Try and spin a Gear Driven unit by hand, now do the same with a turbo, you will see the difference right there.
You can actually blow air out of your mouth into the exhaust in on a turbo and it will spin. Try that on a Gear Driven unit!
