I installed relays on my 1972 last year. I mounted three relays (low-beam,
hi-beam, and horn in the engine compartment between the fuse box and the
plate over the hole for where the pedal box goes in England. I pulled power
(via in-line blade fuse) from the battery side of the solenoid. The wiring
harness runs right beside there, so I was able to cut into the wires that
are feeding the headlights. I soldered in bullet connectors at that point so
that if anything goes wrong, I can bypass the relays in 30 seconds or so.
The wires coming from the switch control the solenoid and the solenoid feeds
the wires going to the lights. Simple and clean. Yes, I think my dash lights
are brighter now and I KNOW my headlights are brighter as well as knowing
that my switches will last much longer now. No need to use a relay for the
I have heard people recommend that the inside of the gauges be pinted white
or silver to improve the lighting.