I see the motorcycle mount & harness for the 665 & 660 are the same, part no. 010-11270-03, which can be mounted then run into the fairing and hide all other wires and hook-ups (power, mic, MP3, etc.) However, for the 665 you need an XM antenna wire, the GXM 40™, part no. 40 010-00730-00. So I assume those who buy the 665 and want XM radio in it will need to run two cables from the 665 instead of the one. If true, that's unfortunate that Garmin didn't update the main harness on the 665 for the GXM 40 antenna to plug it into. So if you want to take your Zumo off the bike when stopping, you can't just use the quick disconnect. You have to quick disconnect then pull the XM radio wire out of the Zumo? Is that how it works with the 550?