Free Up Horsepower. A set of SR Performance Underdrive Pulleys reduce parasitic drivetrain loss by cutting down the amount of power your accessories take up, these underdrive pulleys will free up 10-15 horsepower, without sacrificing cooling and charging functionality of your Pony.Premium Quality Construction. CNC-machined from lightweight aircraft grade quality aluminum alloy for strength and durability, these SR Performance pulleys feature a bright polished finish that will give your engine bay an eye-catching high performance appearance.Easy Installation. These SR Performance Mustang Underdrive Pulleys installs quickly and easily in under 2 hours with no modifications required.Application. This SR Performance 3-Piece Polished Aluminum Underdrive Pulley Kit is designed to fit on 1996 to 2001 GT Mustangs equipped with the SOHC 4.6L V8 engine and the a long water pump (bowed out face). Reuses factory belt.