Hi, I'm new to this forum. I would like to update the map on my Kenwood kna-g510 unit but can't find any instructions or for that matter which map I would need to use. I plan to update the firmware on the unit as instructed on the garmin site (KNA Series, Ver. 4.20, as of Mar 09, 2012).
As for the map, the garmin site latest download for my unit is City Navigator® North America NT 2013 Map Update for Kenwood MSD. So I'm not quite sure which map this equates to on this site? As you can see, I'm pretty green when it comes to this but with the right instructions I should have no problem.

Thanks in advance

First you have to know that Kenwood devices not the same as original Garmins at all. You must find out, how the update procedure of your device goes: via USB-cable, USB-stick or Sd-card. When you know this, you should download an unlocked image of a City Navigator map of your choice (v2014.40 or 2015.10 if available) and copy it in folder Garmin on device, stick or sd.

Yes, so it does have an sd card slot.
Is it as simple as to download City Navigator v2014.40 and extract all the files to the sd card and away I go?

Better to extract the files on PC and then copy the map image in a folder named Garmin on SD. If not yet, rename the img file to gmapsupp.img or if not works to gmapprom.img.