read here for instructions
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for 14xx it's better NT map, you can have problems in address search with NTU
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Download from CNE NT thread here
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City Navigator Europe NT 2013.10 UNLOCKED IMG and copy in sd / Map folder

GMAP3D.IMG , unrar and copy in the same Map folder in sd it should be unlocked , if not, run on it the unlocker you downloaded.

D2504080A.JCV and copy in sd/Garmin/JCV folder.

You should have Gmaptz already in your gps , anyway you can use the one you downloaded from this thread , copy in .System in your internal memory.
If you have preloaded original maps in your nuvi , backup them all along .unl and .gma files in your pc and then delete from Nuvi before copying the new ones.
Take a look at
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if you have doubts