Easiest way to splain it, you move the sensor down and it advances your timing a few degree's. I did it last night, seems to give a bit of pull on the higher gears. Idea being that you will get better mpg, and a bit of hp. I had a car full, 87 oct, and driving pretty hard and didnt hear any detonation or pinging. If you are worried about deto then toss some higher grade gas in for peace of mind.
To do.
-Get in the wheel well of the passanger side, (I had my wheels off painting calipers anyways so it gave me TONS of room)
-Take the cover off, 2 bolts and a phillips head plastic screw deal, and then two more on the undercarrage splash guard.
-When thats out of the way you look for a metal (04 and 05, mines and 06 and it was black plastic) piece that is held on by 2 8mm bolts. The AC belt will be in the way of the bottom one, push it out of the way to loosen.
-The sensor is slotted where the bolts go through, so you can push it down a 1\4 inch or so til it bottoms out on the screws that you loosened. Tighten the screws back up, not too hard though, snug them.
Done.