608 - Harmonically Damped - Underdrive Performance Pulley Kit (986, 987, 996, 997)

Regular price $500.00
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608 - Harmonically Damped - Underdrive Performance Pulley Kit (986, 987, 996, 997)


The RSS Harmonically Damped Underdrive Pulley is ideal for engines that are running light weight flywheels, engines that are built - bored/stroked and engines that are driven hard.

  • Offers improved HP & TQ by reducing drag from the power steering pump, A/C, water pump and alternator without detrimental effects on said ancillary systems.
  • Dampens/reduces internal engine harmonics for improved engine performance, efficiency and longevity. 
  • Recommended for street or track use

Fits on all Porsche 986, 996, 987, 997 models. Does Not Fit 2.9L (multi hole crank pulley pattern), DFI engines, GT2, GT3 and Turbo.

Installation tool (wrench) and new OEM Pulley Washer included:

Dyno Image shows HP & TQ gain on 2005 997.1 Carrera S:
Baseline Dyno Run Mods: OEM Crank Pulley, OEM Software, Cargraphic Headers, Hi flow 200 Cell Cats, and Medium Sound Cargraphic Sport Mufflers
Modified Dyno Run: Added RSS Pulley (Part #608) to baseline car with existing mods:
+16 HP / +8 ft lbs TQ

*NOTE: We recommend using/sourcing a new OEM Crank Shaft Pulley Bolt for your specific vehicle when installing the RSS Pulley. (Not Included with 608 Kit)

We recommend using the appropriate length belt RSS # 6PK which can also be purchased on our website.


Just kidding! But it's a very vital piece of our process!

MINI Cooper Paceman R61 (2013 - 2016)

2008-2014 –   R55 Clubman S & Non-S
2007-2013 –   R56 Hatchback S & Non-S
2009-2015 –   R57 Convertible S & Non-S
2012-2015 –   R58 Coupe S & Non-S
2012-2015 –   R59 Roadster S & Non-S
2011-2016 –   R60 Countryman S & Non-S
2013-2016 –   R61 Paceman S & Non-S


2008-2014 –   R55 Clubman S & Non-S

Why choose us?

All our manufacturing is done in the USA

We design, engineer and manufacture our various parts in our CNC shops across the United States.

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