Whats the best way to put a sound system in a golf cart?

now im gonna buy the amp for pretty cheap it wont be puttin out to many amps and im gonna get some subwoofers and speakers to hook up to the amp i will just use a ipod to plug into the amp so there wont be a deck but it only has a starter generator in it instead of a real alternator what would you suggest doing should i put in an alternator with another battery or is there a better way