if you have an obd remap by one of stus dealers, the dealer simply plugs in, and extracts the required files, these are emailed over to msd, who alter the map as required and send it back, the dealer then flashes the new files into the ecu using the same method as extracting them.

a record of the std files are saved, so it can go back to std very simply.

the new maps are pretty much invisible
i belive stu changes the checksums aswell