I really doubt there is actually a government regulation against this (although they could technically site you under the provision that requires all lift truck modifications to be approved by the lift truck manufacturer). That being said, I think it is a bad idea from both a safety standpoint and from the point of your coworkers that will be forced to listen to whatever it is you think is music whenever you drive by them. Then everybody will have to get their own radio and you'll have radio wars as each person turns theirs up to express their individualism. Yeah, that's a great idea for the workplace. But why stop there, why not go all the way and pimp your ride? A complete sound system with thundering speakers, custom paint job, ground effects, custom rims, custom upholstered seat and matching dashboard, custom knobs for the controls, maybe a dvd player and a mini fridge.