Here is a link how to install relays on the classic Stang for Halogen headlights. I did this on mine and it works great. The Halogen bulbs can make the classic Stang headlight switch circuit breaker shut off when on highbeam, not cool at night, trust me on this! With relays, you no longer load the switch and wiring, it's an easy and safe upgrade.
Brighter Headlights