Often/should be used on stock lights but few people do. Technically you'll need two relays, one for low beams and one for high. Unless you use two relays for the low side or tap into your stock wiring system BEFORE the lightbulb out reed switch, or mess around with diodes, the easiest solution is to unscrew the lightbulb out light on the dash or else it will be on all the time.

Just take a std or heavy duty relay (std is 30 amps..hd is 40+) and ground one side of the signal/coil. Wire the stock high beam or low beam hot side, depending on whether you are working a high or low beam relay, to the hot side of the signal coil. This circuit turns on or off the relay.

Then take a 12 to 14 gauge wire from the battery to one side of the relay switched circuit and the other side to the new e-code high or low beam.

If V-marine didn't supply you an H4 socket, you'll need to get one from somewhere...I think a later model Saab socket for HB4 or somesuch will fit if you can't find a motorcycle socket at an autoparts store. Don't forget to fuse the wire from the battery no more than a foot from the battery or accept the possible risk of a fire from an unfused line.

Watch out for case-grounded relays if you happen to use an old metal relay hanging around the garage...some of them only have three tabs on them...the ground is the mounting tab.

The relays will seriously minimize the load on the headlight switch and maximize the voltage delivered to the lights.