I spoke to my dealer about retro fitting it, and they told me whilst it can be done $ wise it was not worth it. After doing the calculations, it worked out to be $5k more than it would have been to order it when I got the car new from factory.

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05 X5 Diesel, Toledo Blue 19's, Panaramic Roof, Sportspack, Bluetooth & Tint...........
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive, well preserved body, but rather to skid in sideways - beer in hand, body thoroughly used up, screaming WOO HOO, what a ride!