Use your existing bulbs and harness for the corner lights, you can also use the current a regular H4 harness. I took a look at one of my harnesses on the headlight yesterday and saw that one was the USDM and the other was the JDM. I didn't much bother with it because they both work, but just get some USDM headlight bulb harnesses and you will be fine. I haven't had to toy with the prongs on my bulbs or anything, it has always plugged right in.