BMW Z8 Underdrive Power Pulleys 

Reduce parasitic loss of power on your BMW's engine by safely under driving the belt driven auxiliary systems. Reducing this drag on your engine results in MORE HORSEPOWER AND TORQUE to the wheels of your BMW. Our BMW underdrive power pulley kits are specifically designed for each BMW application to make the best power while maintaining stock driveability and reliability, eliminating potential downsides. Others may advertise "their" pulleys boasting more power, but we concluded that for street and track driven BMWs, ours are the best size and design to ensure both your engine and it's belt-driven systems (alternator, water pump, power steering etc) are well within safe operation. We run these under drive pulleys on our own BMWs, so we would not want them any other way.