Snow ball effect!!
Something else, you can rewire your headlights with relays and bigger wiring. That will eliminate a lot of load from the existing wiring. Goody did this with his H4 setup. You can buy as many amps as you want, but all you're doing is trying to pass it thru the same 50 year old wires that arent designed for the load. You can also replace the alt pulley with one of smaller diameter. So it spins facter at idle.