Mounted the XM antenna (GXM-30) for the Garmin Zumo 500 today. Used a Kuryakyn inspection sticker plate (part #9168) mounted to the right side mirror post.
Drilled two 5/32" holes in the Kury plate, using the Garmin antenna's steel baseplate as a template. Screwed the baseplate to the antenna from below (screws & baseplate provided with the GXM-30 antenna). Used two screws and nylon locking nuts to secure the baseplate to the Kury plate. Screwed the right side mirror post through the Kury plate's mounting hole. Easy installation, works great, looks good and is pretty secure. Pics below.
Now it's time to go out riding & enjoy the XM radio.............