I recently installed a XM Radio in my 2006 S Convertible. The unit is a Delphi SA10276. Purchased it at Costco for $70. There is a $50 rebate for a net cost of $20. It plays through any unused FM frequency in your radio. The power connector plugs into the cigarette lighter and the antenna is a small magnetized unit that sits on the front edge of the roof. The back of the cradle has a strong adhesive that attaches to the dash. The receiving unit can be removed from the cradle for safekeeping, if necessary. The antenna wire is routed along the top of window and then inside the trim on the right side of the window. From there is goes down the door jamb, under the glove box and the up to the unit in the small trim indentation in the dash. The power cord comes up from the cigarette lighter in the same indentation. The unit comes with something called XM SureConnect. It involves an extra wire to the car's antenna. I experimented with it and the reception didn't seem any better using that feature so did not install it. Pictures attached.

 

would that not interfear with the Airbag deployment? or is the newer Mini's with the single trim pice have an airbag that comes from the top of the dash

 

The airbag deploys from the top of the dash.