Ahh, gotcha.
Yes mate youve pretty much answered your own questions.

Mapping from base, which is what i call it, is all a matter of "Educated guesswork"

Remember that we are constantly modding stuff for our Modem Dealer Network and they obviously give us feedback until the files are perfected..

Add that to the number of cars we live map and we are pretty well educated to be making the guess

There is "NO" substitute for doing it live though...