Suspension refresh, at 110,000 miles. It's pretty challenging to source some kind of non-oem approach to the struts and shocks for a 4.4i with sport package. At end of the day, I used the Stage 2 suspension kit here:
BMW X5 (2000-06) - Suspension - Page 1
along with these additional pieces:
BMW X5 Front 6 Piece Control Arm Kit By Meyle
BMW X5 Rear Ball Joint OEM
and a set of Powerflex subframe bushings.
The Pelican Parts kit is very nice - thorough and complete with all the incidental parts for the job included, excellent quality and fit throughout. My mechanic had a lot of good things to day about their product.
If you've run out past 100,000, you should really think about doing this kind of a refresh. You'll be very happy with the results.