You can actually do a "hard write", and override the PCM with a new file/VIN. Sometimes it says that the PCM file / OS do not match, which is normally not a big deal. The worst it can do is brick the PCM, or make it impossible to use HP Tuners at a later date if these don't match. There is a way with all tuners to lock the pcm, but I've never locked any of mine, it's not magic and not a big deal to me if anyone sees what I do.