Thanks for the response. 2 out of 4 of my Garmins are LM series and don't have problem with updated maps as it can easily and freely done on Garmin Express. But the remaining two, 250W and 1300 are NOT LM series, hence the reason for being in this forum. I'd like to delete the pre-program map and replace it with an unlock map from here. But I have hesitations as there are other two associated files with the gmpprom.img files. One in particular is the checksum file which checks for authenticity of the image file. Obviously, a downloaded file from here I believe will not pass the checksum. For now I just have to keep the supp image file until I can get a concrete answer or a gmpprom.img file that comes with its own checksum file. Thanks again.