Fits CLS63, E63, S63, G63, CL63

The Ultimate Performance and Design (UPD) M157 BiTurbo Underdrive, lightweight and strengthened crank pulley is designed to increase power and torque by slowing down the rotation of all the engines accessories.

By providing a much lighter crank pulley made of billet aluminum verses low cost cast iron used on the stock crank pulley: Your throttle response, engine performance and MPG will be improved and turbo will rev much quicker.

Using latest design and finite analyses software, plus real world testing, UPD is able to design a billet underdrive pulley that greatly out performs the OEM cast iron crank pulley and much higher quality, precision balanced CNC performance crank pulley.

Throttle response and turbo spin up is improved.

Features:

• Developed by UPD using state of the art SolidWorks CAD, FFA software and live road testing.
• CNC Machined from 6061 billet aluminum outer pulley and hardened steel inner pulley. (OEM pulley is crude cast steel)
• Anodized black to preserve , protect the aluminum and retain an OEM appearance 
• Reduced weight: pulley i5.7 lbs 48% lighter than the OEM steel pulley 
• Precision Balanced within less than .1 gram on. 
• Lifetime warranty – Original purchaser