you can download maps on to a sd card and upload them into the voyager i havent tried it yet they explained it on the cd that comes with it
As I recall, what they call maps are actually routs or tracks. Maps are overalays like base map, topographical or satellite views. Some examples are like this.
This is track converted to a rout with several map overlays. This first one is just a base map:

This one is still a base map but with terrain added:

And this one is a topographic map:

And finally my favorite, the Satellite or Arial view map:

So...yeah you can go to their open source and download tracks or routs...what they call maps...and upload them into the voyager from the SD card but not any of these overlays which everyone else calls "Maps". Still love my Voyager. Has helped me many times and the GPS is more actuate then many others.