Hey Freiherr, yes I'd like to do a full audio re-theme, here's hoping for the future.
Thanks for the shares Mr Pinbologist. I worked on a playback system which was delivered from Canberra to Melbourne. Originally the new audio was to be added into the existing audio path but there were some problems. I tested my system on a similar machine locally but it didn't work so well with the proper pin and it's a bit hard to do system installation via phone so an additional amp and speaker were added.
With a bit of luck and more R&d I will have an Arduino based system sorted round the end of the year.
Thanks to Mike @Homepin for advice and light trigger boards kits.