As indicated in the first post I ordered the tips from cyba (
http://www.e90post.com/forums/showthread.php?t=281932). They required about an inch to be cut off but as you can see they worked well. I simply ordered the 550 diffuser from my local dealer.
I still have the vehicle and the tips look as good as the day I put them on.
Bill
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2011 535i xDrive, Dark Graphite Metallic, Veneto Beige Dakota Leather, Technology Package, M Sport Package, Executive Package delivered Christmas Eve '10, Mods - quad tips, 20% tint, JB4.