Curious about gains with a 15% pulley. Does it make a big difference in performance? 06 MCS with 21K miles. Will this kill the warranty? How big a job is it to change the pulley? Thanks for any input!!

 

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When I installed the pulley on my 2006 MCS with 4k miles or so I immediately noticed a difference. It is probably the biggest performance gain for the money. It's not a night-and-day difference but one that you do notice. You will feel some more low-end grunt. When putting my foot down even in second gear the tires would scramble for traction, which didn't happen with the stock pulley. You can also hear the supercharger spinning at a higher RPM which I loved. In regards to warranty, every dealership is different but as long as the pulley doesn't cause a component failure, it shouldn't impact warranty. Be as prudent as possible (when you replace the pulley you should also replace the belt with a smaller belt and it is suggested to replace on a regular basis, install colder spark plugs and a belt-tensioner-limiter is recommended)

There are many threads on installation but they usually involve lifting the engine slightly out of the car. I bought my pulley from Randy Webb and followed his instructions.