In the machines I put L-Pads in like that, there was no interference with anything. I'm only drilling through the steel faceplate and the plastic panel behind it, not in the coin chute or anything like that.

I don't drill holes in any machine I think is "special" Of the 2 I've drilled, one is the Crazy Shaman S/N 14892 (not rare not matter what the ad writers at PP say :-) ) and the other is a Cray Fish that Zcore made into a Spongebob custom (beautiful, clean machine, but not collectible anymore, if it ever was.)

You'd be surprised how often you adjust the volume when the knob is right there. If I'm alone in the house, I'll turn it up and enjoy the quality of the sound, but after the kids head for bed, I can turn them way down. Also very helpful if the phone rings in the middle of a bonus round.

The connector in the picture is the connector I pulled of the speaker terminal next to the resistor. If I want to go back, I just unsolder the resistors and put the connector back where it was. Older machines seem to have the speaker wires soldered on. On those, I clip the wire just long enough to be able to reattach it and shrink wrap it later if desired.

The wire was just lying around in my electrical box. I believe it was speaker wire left over from a cheap car stereo speaker install. It is multi-strand 22 gauge just like the machines come with. I'm pretty sure you could find something similar at Radio Shack