VAC Motorsports’ Ultra-Lite Underdrive Street Pulley sets are a great way to free up horsepower and torque from your S54 engine as found in the E46 M3, late Z3 M and Z4 M.

Manufactured from 6061-T6 billet aluminium and precision balanced and inspected for zero-runout, these pulleys have no adverse affects on reliability, noise or vibration. Made in-house at VAC Motorsports in Philadelphia.

Claimed increases of 8hp and 7lb ft at the wheels on an otherwise standard engine. Includes underdrive water pump and power steering pulleys, along with brand new OE-type Contitech serpentine belt.

See here for replacement belt.