MINI Cooper S R52 R53 Reduced Supercharger Pulley 16% M7 Speed Tuning Eaton M45

So why choose a M7 Speed 16% reduction pulley?. Shoulders are added on both sides of the pulley to help prevent the belt from walking off of the pulley surface at high engine speeds. The main pulley body is made from billet 6061-T6 aerospace grade aluminum alloy.