I'm in the process of lease termination of my current 2004 X5 and moving into a 2008 X5 . A few questions for anyone. One, I just received notice of a reservation for Performance Center delivery (I did it in 2004 - really worth it!). I understand that I will get a production number today. Question: Once I get that number I believe that I have read in these forums that I can call BMW and confirm delivery, etc...is this correct and what is the number. Two, is the premium sound package worth the $.