I just had my 4.8i with self leveling lowered with H&R (Race) springs.

For the self-leveling X5's, the H&R spring kit only comes with 2 front springs:

http://hrsprings.com/scripts/appguide.php?Mode=Application+Guide&SubMode=Find2& Year=2008&ModelID=125&q=2008%20|%20BMW%20|%20X5

You can either go with sport (1.2 inch front drop) or race (2.0 inch front drop) Once you install the front springs, we will need to get custom shortened links for the rear which adjust the rear height. The links which the shop installed on my rear were about 1/3 of the length of the stock links.

Good luck, I will be posting pics soon.

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2008 X5 4.8i
Space Grey / Tobacco Interior
Premium / Sport / Premium Sound / Technology
214's / H&R Springs 2.0" Drop all around (3/26/09)
www.ewirelessexperts.com