JCL, thanks for clarifying what I may be faced with. Unfortunately, the my X5 dealer is not a Dinan dealer. I would have to get the tune installed from a different dealer from whom I got my CPO 128i. My relationship with my BMW dealers have been limited to maintenance issues, not with any major issues that would bring out their true colors. May be I should get the M performance package with its measly 15 hp and 30 ft-lb gain, but the difference between it and the standard engine is barely noticeable.