overdrive or underdrive pulleys to the engine to increase horsepower which makes it to the wheels instead of being wasted on the pulleys. sorry im am very new to the maret for owning a vehical like are you talking about putting a diferent belt on ??? besides the serpintine belt ?

Basically it works like this. The pulleys on the belt-driven accessories of an engine all rob a certain horsepower from the engine to run the accessories -- alternator, power steering, etc. This is based on the size of the pulley to get the rpms necessary to run the accessory. By putting larger or smaller pulleys on it is possible to run the accessories at the proper rpms but with less wasted energy than with the stock pulleys. This may require a different belt as you are changing pulley size. A good performance or speed shop or even Advance Auto will have a listing if these pulleys are available for your vehicle's engine. They are typically sold and replaced in sets.