Update:

I am 80% done at re-generating the original vxml file using the data in the encrypted voice. When done, you will be able to take the audio samples and the .vxml file and re-generate the encrypted VPM. Yes, this means you can alter the voice files and/or the phrases structure and create a new file using Voice Studio or Voice Creator.

One thing is bugging me a lot: Should I let you decrypt the locked files or not? If I let you do this, I may have Garmin and the voice producers on my back. Locked files are files that can only be played on a single GPS. If you decrypt a locked file and recompile it, it will not be locked anymore and it will be playable on any GPS. I know this is cool for you, but not that much for the copyrights holders... One alternative is for me to make the Voice Creator equivalent and let my program make the recompile. This way, I would be clever enough to preserve the locked bit. You can still alter the voice, but not unclock it. This would be a great workaround, but I would need to work a lot to emulate Voice Creator. Hum! Maybe a next phase...

Opinions are welcomed!