The pulley upgrade that seems to be a no brainer, has several people asking about warranty issues. If I'm not mistaken, the pulley upgrade is part of the approved JCW package? Is this an issue of who performs the upgrade vs. the upgrade itself?

Spike

 

I think that it's more of an issue of the JCW upgrades being a "factory" upgrade which keeps the warantee. Any "non-factory" mods, even if they are the same as the JCW mods, have the potential to void the factory warantee, if MINI can prove that the mod caused the failure.