What would it change if I do so? I've done it in a form of mod in the .wad form.
YD used "MM4BOSS.nsf" to replace the mm4 boss theme.It did confuse a few people, I think, but is alright otherwise, so it possibly WOULDN'T matter to other people,as long as the music has the right name, but I DO NOT think making a WAD of a music replacement might be good either.Did it work?