For those who may be interested in the xm radio install, I finished installing my Alpine CDA-9820XM with the xm feature. The antenna is fairly straightforward with the exception of the 2 styles of XM antennas that are avail. The first XM antenna style is a dual feed going to the head unit. The second is a single feed type of antenna. Unfortunately, I purchased the dual feed antenna that was not compatible with the Alpine 9820. I ended up getting the correct antenna (the single feed wire). It is quite smaller that the dual feed antennas, which I was thoroughly impressed with its low profile, look. So small you barely notice it! I mounted it above the rear window and fed the wires through the weather stripping, down to the passenger side door jam, across the doorsill to the kick panel, and then routed underneath the carpet to the head unit. It's quite simple and straightforward.

Bottom line is that if you decide to mount the XM feature make sure you get the proper antenna for your head unit!