New Voltage

The alternator is by far the best location to power your headlights when adding the relays. One of the largest benefits is the reduction of amp draw through the firewall plug and the associated small wiring. The lights literally have their own circuit now instead of using the undersized and 35+ year old wiring. Numerous websites recommend this approach including a lighting consultant friend of mine who deals with high end HID lighting and such.

When you do this be sure to use fusible links or the appropriate fuses between the Alt and the relays. I installed a 78 Amp alt and used 2 seperate 12 ga wire and 16 ga fusible links to power the relays.