Been playing with a GUS PNP lately. I used downloaded drivers as I have no CD.
The GUS PnP doesn't really work in Win98 - the various drivers and applications do not install properly. Reverting to Win95, it goes fine.
In Win95 you get an icon in the control panel that enables you to load different patch sets. You will need ram big enough or they don't load of course.
The 4mb sets are for Windows. In dos you get the gf1 patch sets, so it should sound the same as a non-pnp gus in dos games. I understood that some dos games contained there own gus sounds, in which case i suppose you can't change the sounds of these.
Patch sets need to be set up in the iw.ini file I think. You need to set up a path or filename.
The 4mb sets are hard to find as there was a copyright issue - most gus-related sites do not have them. You get a pair of files, gsfull4m.fff and gsfull4m.dat. The dat file is 4mb in size. It took me a few hours to track them down, and it seems I didn't save the link. Duh!