NT maps are no problem and XT has no gma protection so you can unlock a locked image file with just a JM generated unlock code in a .unl file. But as Roger has pointed out, if the map is unlocked by gimgunlock or similar that unlock code is not needed. Check you've named the file correctly, XT cannot recognise 'anyname'.img. Try gmapsupp.img or gmapprom.img as names and ensure the file size is under 2GiB. The maps go directly in the Garmin folder.
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