I agree with JCL. I had a 2000 540 Touring with a Dinan S2 package and Stoptech brake kit installed. The investment was in the $6K-$7K range. When it sold, it went for the exact same price as a comparable non modified 540 Touring. Mods unfortunately do not increase the sales price. You've got a nice X5 that will sell quick for the going rate. Good luck.

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2006 4.8iS Black/Black with custom Audison Voce/Image Dynamics sound
Production Date - 10/05