MRT Engineering M50/M52/M54 35% Underdrive Alternator Pulley. A must for all fast road, track and race cars.

By reducing the drive ratio of the alternator, this pulley will increase alternator life and also reduce parasitic losses. Choose from Bosch or Valeo alternator types in the options.

• Made in Finland from billet aluminium
• Bosch-type replaces BMW part no 12311432988/12311703736/12311726139
• Valeo-type replaces BMW part no 12311713945/12311436636/12311703735/12311403026
• Increases alternator life
• Decreases horsepower losses
• Longer serpentine belt may be required