The sound software is tied to the graphics and logic software, if you put another sound simm, you will get an error at boot and the game will be unplayable. Board mods do nothing on gaming machines. Gaming machines are highly regulated, so when their software is certified, it needs to prove to the jurisdictional authorities that everything in the system is as the manufacturer intended, otherwise you get tilts. There are only a few non-play related modifications that will work, typically lighting and cabinet mods, but when it comes to the software, there's little or nothing you can do about it.