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We are currently experiencing longer than average ETA's due to global supply chain issues. We apologize for any inconveniences this may cause.
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ESS E9X M3 Underdrive pulley 6/08-2013



Our specially designed and engineered S65 underdrive pulley kit is a great addition to the M3.  This is done by improving power through reducing parasitic drag on the engine from slowing the speed of the alternator, water pump and AC compressor components. Hp Gains are approx 10-20hp depending on condition of car, climate, and other performance products.

For maximum performance, we also suggest pairing our full exhaust system with our specially designed performance software



  • CNC hard anodized S65 crank pulley.  Precise and measured belt groves and bolt holes.
  • Serpentine belt
  • Single/ double-sided power steering & AC belt



BMW changed the Accessory belt configuration from a single-sided (power steering & AC) belt to a double-sided belt for the E9X M3 that were produced after May 2008.


2007-5/08 production date has single-sided power steering & AC belt.


6/08-2013 production date has double-sided power steering & AC belt.