About changing a map, you can do what you like with it on your computer but you cannot re-export it under your KUID.
If you have TRS2004 then you can use TrainzObjectz to do the replacement. The new TS2009 will allow you to change tracks and in either case the change should not cause a problem, the new track will still link to the original vertices.
In TRS2006 changing in the config.txt does not work, when you commit the file the number will be changed back to the original. I think there is a version of Trainzmap that works in TRS2006, that should allow you to make the change.
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