If you are going to run on the street you need a 16 volt alternator. My old dodge has stock lights and it just made the headlights a little brighter. Factory 12 volt system alternators operate about 14.5 volts anyway, so you are not really increasing the voltage that much. The only issue I would worry about again on a street vehicle, would be any electronics on the car like a radio. I know MSD does not have a problem with 16 volts.