Headlight Relay Kits
Just adding to the conversation here.
I've done hi/lo relays on my dart after upgrading to some pioneer led headlights.
I have already done the big 3 upgrade and completely isolated the charging circuit so I do not have the ammeter and the "P" circuit [everything that was spliced with that old ammeter wire] is isolated after the battery now.
I added the relays behind the battery to keep a short power (with each fused) and a short ground run for both of them.
The old wires were converted to the trigger wires instead (and the relays switch which one is on) at that location and new wire was ran with the relays and new lights etc.
Besides talking or searching on here,
the12volt.com is a good resource for various wiring and breakdowns for relays too.
I have read nothing but great compliments about Crackedback's kits, I just enjoy doing things myself.