Originally Posted by Hapa88

On my Mazdaspeed3, I had a relay wire harness for both my fogs and one for my headlights (2 harnesses total). They were both able to reach from the battery in the back of the engine bay to my headlights and to my fog lights. I mounted the ballasts to the back of my front bumper beam.

Also, a quick note to mount the relay such that the wires (or prongs) are facing down (relay is mounted higher and the wires go downward). If the relay is facing down (with the wires coming up and out of it), it has a tendency for water to travel down the wire and settle on the relay. This happened to me when it rained in CA and it shorted out my relay and I couldn't use my headlights. Luckily my foglights still worked. . I went to PepBoys and bought a replacement relay and was back in business, but be sure that water doesn't settle on it! Just a lesson learned to pass on!