Hi,
I'm very new here.
I have updated my 760 a couple of times with Garmin .img map files that I have downloaded from torrent sites and they worked well with that being the only file I put onto my 4Gb SD card.
Then I downloaded "Garmin.City.Navigator.North.America.NT.2021.30" that came from here, and in it I found a bunch of files that I didn't understand the purpose of ... but I found a folder in there called "City_North_America_2021_30" ... and inside there I found 5 more folders ... the largest of which was "IMG", and in there was "gmapsupp.img" ... which seemed to be the same name as the older file I was replacing.

I thought all was well, but when driving around using the Nuvi 760, I found that the navigation was very spotty ... that the roads were not all there ... that most of the time it showed me not driving on the road itself.

Did I do something wrong by just installing the "gmapsupp.img" file onto my SD card?
What else should I have done?

Thank you for any pointers, tips, etc. !!