@351_DD-1: yes, I have PS2 tach system and PS2 smoke, which are both original with the Bantam engine. The tender is the only thing that was loco-sound, and it was just a speaker and a pot.
John, would changing the sound file risk the 5V board in any way? I'd rather do as little handling of the board as possible, some they're liable to blow up at the slightest provocation as far as I can tell from these boards.