The use of power steering, air conditioning, air pumps, alternators and other power-draining vehicle accessories can rob even the most juiced-up street car of much-needed horsepower. Even the most devoted street car aficionado would cringe at the thought of eschewing these standard vehicle amenities just to get more out of his/her ride. But with the addition of a performance pulley, speed freaks can now enjoy the same creature comforts without sacrificing additional horsepower and torque.

Performance pulleys (also called underdrive pulleys and V-belt pulleys) work by driving a vehicle's accessories at a slower rate than previously set factory settings. The controlled speed means the engine spends less effort spinning the performance pulleys and the other gadgets attached to it. The reduced workload on the engine translates to extra power given to driving the wheels forward. Many car enthusiasts attest to the significant engine boost the performance pulleys provide and this mechanism has now become a standard fixture in modified and even in stock cars.

On the average, a performance pulley can free up as much as 15 hp (horsepower)while costing just a few hundred bucks or less. Most after-market auto parts dealers carry a wide variety of underdrive pulley configurations which allow the car owner the option to tweak or alter the amount of underdrive built into the pulley set. This is a very handy feature for those who want to run a full-speed alternator while still getting gains through the power steering and air conditioning pulleys.