About a month ago, I took my 1/03 X5 to 3 different places (2 high end car audio places and the BMW dealership), and, even with the expert help of Micah at Bavarian Audio Works, they were never able to get Sirius to work with the Nav. I even replaced the radio with the current model and BMW upgraded the Nav OS to v27. The BMW guy said there's an extra wire to my Nav unit that's not there on the 5/03 car he brought in to compare it against. Unfortunately, I'm not sure you can get Sirius to work with the Nav unit on these early '03 X5s without some very sophisticated electronic sleuthing to determine how the wires are configured. I gave up and am now in the process of replacing the whole thing with an AVIC Z1.