i do not think it is a good idea to try to install a second alternator... it could cause your battery to overcharge and that could mean a few terrible things like total meltdown... your alternator is what runs all your electrical components while the motor is running... and too much current could mean a fire from too high voltage.... seriously any sound system you have should be capable to be handled by your already installed alternator... there might be some engineer out there that could hook it up to run properly but i still highly DO NOT recommend you do this...