by B1ng0 » Fri Sep 30, 2022 9:03 pm
"1. what happens to the maps (etc) already on the device (are they unlocked, deleted, or left as they are)"
Only one particular region in the device's memory is affected, that's region 14 (hex 0E) which contains the main system software, a.k.a. the firmware, which is patched to remove Map Signature Verification (MSV). That doesn't affect existing official present or future maps such as Lifetime Maps or other maps purchased for the particular device, it simply allows devices which have MSV in their firmware to use unofficial unlocked maps.
"2. If i want to add different maps to the device do i need to delete the original maps (depends on 1 above)"
No. The unlocked maps you add will be for different continents or countries than your device's initial entitlement. Conflict between maps would occur if you had overlapping areas or duplicated maps of different version releases.
"3. What are the best maps to consider NT or NTU or does it not matter when the firmware is patched ?"
Drive 51 can use either NT or NTU data however if an NTU version is available (Europe is particularly relevant), the corresponding NT maps won't have compatible ancillary files like JCV (JunctionView) or ASR (Automatic Speech Recognition) available for NTU-capable devices like yours, slightly different ones are made for NTU-capable devices. If an NTU version isn't available (e.g. North America, Australia/New Zealand etc.) then the NT mapping is suitable and the relevant additional files are available.