Basically this mod lets you use a 9005 high beam bulb in a 9006 low beam socket.
The 9005's are 65w a piece, whereas the 9006's are 55w, and are rated for more lumens (light output) as well, 1700 vs. 1000.
So you should be looking at a 70% increase in light output, with a slightly different beam pattern too (a bit more hot-spotted, but I could be wrong about this).
Anyhow, here's the mod:
You basically file down the notches inside the electronical connector flat, and then make the one hold-down-tab opposite the electrical connector narrower.
I'm going to try this myself really soon
I found this link through saturnfans