Region 41 is your NVRAM (Settings, Favorites etc and a lot more data) I call it the Nuvi's registry.
Region 16 is the logo.bin file. (First Spash screen when the Nuvi boots) it has a part number embeded in it as well.
Backing up region 16 is exactly the same as backing up region 41 except that you type in 16 instead of 41.
example of update.txt