Good writeup. I purchased parts from and consulted Daniel Stern to fix the headlights on my 97 Legacy GT.
I bought the wiring harness kit and Osram bulbs from Daniel, totaling just under $100 IIRC. I bought a bunch of 10 gauge wire in preparation, which in retrospect was overkill but it worked.
The biggest roadblock to upgrading my headlight circuits for me was actually assembling the wires, headlamp sockets and relay wiring. Sure, I understood where to tap in and how the circuit should work, but physically assembling the stuff was a bit daunting. I had a bag full of parts I've never seen before and wanted to make sure I assembled them properly. Daniel provided a parts list of what goes where, which helped, and the rest was reading the book below & searching for pictures of assembled connectors so I could figure out how they were supposed to go.
This book helped a lot with the specifics of automotive wiring and troubleshooting:
http://www.amazon.com/Automotive-Wir...2923695&sr=1-1
I already had a nice Klein wire stripper from my college days and added a Klein crimper & another quality cutter. These were probably a bit over $50. Cheap tools will certainly do for a one-off or small project, I just prefer to buy quality tools once when I know I will use them again.
The process was pretty straight forward, but my first attempt at firing it up failed. The various diagrams I had found outlining which pin was which for the headlight socket used differing names for common ground, common feed, etc and totally turned me upside down on which pins I needed to light up to trigger the low beam & high beam. I finally sorted this out and hooked the right inputs into the new headlight socket.
My problem was compounded when I found that the person who had previously repaired my car put in a pair of shitty headlight sockets, so just piggybacking off the sockets to trigger the relays wouldn't work. I also then found out that there is some problem with the wiring between the relay and the light for the driver's low beam, so I couldn't use THAT to trigger the low beams. I had to tap the wire from the passenger's side, which works fine, but it added more to my testing and diagnosis when the circuit wouldn't work.
Once the wiring tested good, I broke out the butane torch and closed up the heatshrink connections and taped elsewhere. I applied some plastic wiring loom everywhere I could for that nice clean look. The relay blocks were mounted on the inner fender in front of the battery, and the relays pop right out if I need to diagnose anything.
Overall it ended up being a huge improvement, fixed the driver's low beam that wasn't working, and was a great learning experience.
I'm happy to answer anyone's questions, as I literally came from knowing almost nothing about the process and how headlights work. But first, of course, read Daniel Stern's page on upgrading healights:
http://www.danielsternlighting.com/tech/relays/relays.html
