Hi.
Let me take a crack on this.
I am one of the few people that tried HID's in projectors, and here's what I have to say to help you guys out:

I have gone through numerous of the aftermarket 'projector' headlights. I knew that the light output is INFERIOR to that of stock headlight housings, but to be honest, I just think the projectors look 'cool' Firstly, the projectors use H3... the common fog-light bulb, how could that possibly produce enough light as to one H4 that is double the size and better beam pattern. But anyway, I bought my first Denji set, clear projector (elipsoid) and it was surprising that the light was good. Then I bought black housing no-name brand with blue 'ion' lense, the output was horrible. With PIAA super plasma's the light was like faint and horrible.

I stuffed in a HID Osram 6000K in there and the light was brighter, but the beam pattern simply SUCKED. It was a glow more than anything. I then swapped in my older clear projectors in and the light is much better, although beam pattern is still not as great. I am currently working on transplanting other brand (higher quality projectors) in my headlights.

My advice, don't waste your money on HID's for your projectors (High AND Low) if you want brighter light and better vision at night. If you have too much money and don't care much for effetiveness, then go for it.

For thouse concerned with melting the housing, the H3 bulbs did melt the metal 'paper-clips' that held the bulbs in place, however, HID's do not produce anywhere close to that amount of heat.

I hope that others can learn from my *expensive* mistakes

Hope this helps.