Thanks greywolf! So I was doing even more reading and found out that the h4 bulb that I'm looking at buying is not a HID, but rather a halogen bulb. In fact, it has the same ratings as a H4656 sealed beam Halogen bulb (12v 55W). It even looks like it has the same connectors... so based on this, I don't think a relay would be required, would it? Is this bulb a simple drop and replace?