I am a complete newbie to BMW. Bought on the spur of the moment a 2001 BMW 540iA from CarMax. It has NAV, DSP, no CD changer, 16:9 screen. 46K miles. Had 3-20 Nav software. Found v.27 software, found CD-key for MK-III. Update went smoothly, yes it asked for the CD key disk. I had made one. Plugged an address in and went for a ride and it took me there without problem. You guys are the bomb. That's good.