@ter@
Hard to kill a 3790, but anything's possible. Here is a sure way to experiment without any chance of 'bricking': Put the new additional files on a microSD. The new map-related ASR files and the JCV files will work fine in sd:\Garmin\ASR and JCV sub-folders as will the map itself as gmapsupp.img in the Garmin folder or 'anyname'.img in a Map root folder. The SRD language files must remain in the unit's ASR folder itself however. If you have problems simply remove the card and the unit will function normally.

There is zero chance that any of those files if incorrect would stop your unit from booting though, and in the case of the JCV files your 3790 can probably use either the picture size 400*366 or 212*234.