http://www.steeda.com/store/steeda-u...ustang-gt.html

Get back the horsepower and torque your belt driven accessories steal and start enjoying better performance and gas mileage today!

Steeda's underdrive pulleys slow down accessory speed by about 25% reducing parasitic acccessory drag on the engine. This drag reduction results in an increase of up to 10 horsepower and increased gas mileage!

Steeda underdrive pulleys are the only pulleys engineered through our unique partnership in Ford's technology transfer program to have the proper torsional vibration dampening characteristics for your 4.6L engine. No other manufacturer can make this claim.