I wouldn't bother but just install another OSM map.
Does it replace the older map with current map if updated? to save memory space, since the current map is 6.89gb ..im still thinking if i should update or not because of the file size and if its really necessary. Thanks.
I updated the map via Garmin Express and it say map successfully updated, but when i plugged in the 820 back to the PC the Routable US map update is still showing on Garmin Express. where did i go wrong?