rename map4.img to gmapsup2.img and place in Garmin folder. Repeat the process to unlock the map, and name gmapsup2.unl
I tried this method in my sdcard but with no success. I understand that you could only do this with the device internal memory but I was hoping to have two selectable maps in sdcard (gmapsupp.img and gmapsup2.img perhaps?). Any help is much appreciated.

By the way, I'm using a China made PND.. so it not possible to install software/maps in the device internal memory because of insufficient space.

Thanks!