Dinan's lightweight billet aluminum crankshaft pulley underdrives each of the accessories by 13%, reducing parasitic drag on the engine for a 6 horsepower and 4 lb-ft torque gain.The Dinan underdrive pulley retains the factory harmonic crankshaft damper, eliminating vibration that might otherwise damage the crankshaft. The kit includes all of the necessary mounting hardware, lightweight pulley and shorter belts.This product is backed by our industry leading 4 year/50,000 mile warranty so you can rest assured that you are purchasing the best quality product for your BMW.2006-10 E60 M5 Sedan, 2006-10 E63 M6 Coupe, 2007-10 E64 M6 Convertible Download There have been no reviews for this product yet.