Originally Posted by Mavrick151
If you are worried about your warranty go with the Dinan pulley
To clarify on this, the Dinan pulley includes their own warranty, which a lot of forum members often mistake for an "approved" BMW part. Needless to say - the Dinan parts are very reputable.
We like the Rogue pulleys, which utilize "off the shelf" belts, which can be purchased from any auto part supply house and provide considerable gains.