For a decent low-cost upgrade, you can convert your 9004 lights to use 9007 bulbs very easily. This will not make a dramatic difference, but most people say that it gives at least a little improvement.
- Remove the 9004 bulbs.
- Use a long, flat blade screwdriver and a mallet to snap off the two tabs in the bulb sockets located at about 5 o'clock and 8 o'clock. Leave the tab at 12 o'clock to orient the bulbs (same for both 9004 and 9007). This makes the socket compatible for both bulbs.
- Pull out the rubber moisture plug from the headlight connectors. Note the position of each colored wire. You will be swaping the positions of the brown and yellow leads. This is a difficult procedure that needs to be done in two steps: First you need to remove a piece (the top quarter) of the plastic casing of the connector itself, as it acts as a place-holder for the wires. Second, insert a very small jeweler's screwdriver into the open end of the connector (opposite from the end from the wires) on the top side (the side that you had to remove the plastic place-holder piece). The wires should pop out easily.
- Before you push the wires into their new positions, you should soak down the little rubber moisture plug with WD-40 and pull the 2 wires (and connectors) out through this plug and re-insert them into their new positions, then the plug will go back in nice and neat, otherwise with the wires crossed, it will not go back in very well.
- Insert the brown wire where the yellow one was originally, and vice-versa.
- Carefully push the moisture plug back in, angling the wires so that it all fits back together.
- Plug in the 9007s and go drive really fast at night.
