Gain more horsepower, gas mileage, and accessory life with the ROUSH® 25% reduction Mustang Underdrive Pulley. This pulley fits 2005-2010 Ford Mustang GTs with the 4.6L engine only, and does not work with ROUSHcharged™ vehicles.
The ROUSH Underdrive Pulley dampens damaging engine harmonic vibration, meets SFI Spec. 18.1 and has a diameter that is 25% less than stock. The benefit is that 25% less power is diverted to running accessories, such as the alternator. As a result, more power is freed for performance. This part has been found to increase power by 8-10 hp. Due to the increased efficiency, fuel economy is also increased. In addition, because the accessories run by this belt are being run at reduced rate, their longevity is improved.