I have wanted to do this project for a while. It is more for the "cool factor" and probably completely unnecessary... but I love I love gadgets. Also I once owned a 2005 STI which had adjustable headlights. After swapping my GC, adding the GD cluster, adding the IC sprayer; the only thing my STI had that my GC didn't was headlight leveler motors. Well not anymore:)
Some overseas GC8 Imprezas (In the UK, Prodrive P1s, the "EDM" GCS) came with leveler motors on their headlights. Inside the car was a horizontal switch that would be mounted above the single din radio to adjust the headlights up/down. In the US and in other countries, we got manual headlights. To adjust them up/down you would have to pop your hood and pull out an 8mm ratchet.
There are really two ways to go about adding headlight leveler motors to your GC. METHOD ONE is to buy a nice set from overseas and wire them in. METHOD TWO is to acquire the headlight motors and add them to your US headlights (which requires opening them up). I tried to do the first method, but the headlights sold to me were not in great shape. The chrome reflective material inside them was burnt and cracking/pealing. One of the mounting tabs also broke during shipping. So I was forced to go forward with the second method. I made a video documenting the install:
To open up your headlights you need to bake them in the oven. Pre-heat it to 220 degrees. While pre-heating, strip down everything you can from the headlight. Remove the bulbs, remove the metal clips around the edge, remove the 10mm clip grommets on the side, remove the manual adjustment mechanisms from the back. If you are pulling apart EDM lights, remove the motors. When the oven comes up to temperature, bake one at a time for ~ 12 minutes. The glass should pull off them. If not, heat for a few more minutes. Be careful when separating them as the urethane around the edges will stretch and snap, you don't want any to get on the reflective lens because it does not clean off easy. When it comes time to re-seal the headlights, place verything together, bake for 10 minutes and press them together. I like to bake for 5 minutes first, press them together as much as possible, and then go another 5 minutes and press again.
Aside from the motor, there are two main differences between the manual and motored headlights:
The first difference is the adjustment hole on the back. The manual adjustable headlights (seen on bottom) has a smaller hole for the manual adjustment screw. The motor version needs a bigger hole. This is easy to tackle (just drill it out). Even on the EDM headlights, the hole looked like it had been drilled. I'm sure Subaru made all the headlight backings the same and simply drilled the hole bigger for ones that would accept the headlight motors.
The second difference is the plastic piece inside the headlight that receives adjustment screw or headlight motor rod. On the manual headlights it is made from black plastic and has threads inside it for the manual screw. On the motor version, it is made from white plastic and is a ball socket.
If you do not have the white plastic ball socket, fear not. People have managed to create their own. Some people have hollowed out nylon spacers, some people have found furniture parts to modify. You basically need to make something that snaps onto the motor rod ball and doesn't come off easy. I also read that older Impreza headlights (93-97) use the white plastic pieces, so maybe a set could be sacrificed.
I cover the wiring in the video up above. I opted to go with the vertical 04-05 USDM headlight leveler switch vs using the horizontal EDM switch. I had planned to mount it to the left of my steering wheel, but the switch is a different shape than the GC buttons. I discovered that it is the same shape as the factory coin holder on the center console. I chose to put it there instead.