Steeda SFI approved undedrive pulley for the 4.6L engine. By slowing accessory pulley speed by up to 25% these underdrive pulleys free up horsepower and torque parasitically lost to your accessories. By doing so this can give an increase of up to 10 horsepower and will also increase fuel economy. We also have available the OE approved underdrive pulley for the 4.0 V6 one and half hours installation time.
