Coil/ballast resistor draw drop a whole volt?

Check both sides of the relay to see if the drop is in the relay or before. Then check right at the battery to see if the battery is dropping that much. Sounds like your wiring is plenty good. Regardless, feel the wiring back from the ballast to the battery and look for warm spots.

You did not fuse the wire from the start relay to the relay? You don't HAVE to as the factory wasn't, but I like to run about a 30A fuse in there for catastrophic failure. It would save burning up the harness in case of a short somewhere.