Originally Posted by spiff72

Unfortunately, this isn't the case. If your car came with the 6.1 version (and thus has the 6.1 firmware), it won't reload the firmware from the DVD when you put in the 5.1 DVD. It appears to check the DVD when it is inserted to see what version it is. The only way that we know of to force it to re-load the firmware from the DVD is to disconnect the aux 12V battery in the trunk for a few minutes while you have the 5.1 DVD in the nav system. When it loses power, this forces the system to load the firmware from the DVD even if the version on the DVD is older than what it currently has internally.

If you have 5.1 firmware, and you put the 6.1 DVD in, it WILL load the new firmware off the DVD, since it recognizes that it is a newer version.