I have no idea about stealth part, so I've used Henchman's theme from Hotline Miami 2: Wrong Number. So if you want to change it, select music track that you want, call it "setup", then using RAD Video Tool convert "setup" into bik format, then convert it into movie format by yourself, move your created stealth track (setup.movie) to Assets/music/town_chaos/ and replace old setup.movie by your stealth version. And that's it.