I have a friend's TT XL IQ Routes with old US mapping to update.
I have read a lot of posts and tutorials, esp. Downunder35m's one on "How to get the right Navcore and map working" but I'm not sure about the following possibile way to update.
Rather than empty the file structure and start from an empty device, can I simply patch the existing Navcore (9.510), remove the current map folder ("United_States" v.1010.8923), replace ...