I came upon this in the Steam forums, and figured GOGers should know about it too: http://steamcommunity.com/sharedfiles/filedetails/?id=943382635

It's a rip of the TG16's soundtrack, which you can drop into either the OPL or PSG directories to replace one of the classic soundtracks with the nicer-sounding Turbo version. It works perfectly, but why wouldn't it? The thread also includes links to hacks to make the classic graphics look more like the TG16 version as well, although I haven't tried those.