I have the quads myself but thats only because I purchased my X with them. I always did love the 4.6/4.8i/is tips though, they look great too. but so do my quads to be honest.

If i were trying to find the 4.8 styles though id be searching ebay....

UPDATE: eBay link

Isnt that strange? I cant seem to find exhaust tips for any X5 other then 3.0 (V6) ... Ehh what gives?