you forgot the illegal part of that statement....
Putting a HID in a non projector housing is going to get you tickets from the po po.... Do it right the first time and have focused light like you are supposed to... just aim the headlight almost straight out and you can get that nice flicker as your suspension goes up and down so you still hit them hard with your low beam inside a projector housing. Also if you trim the housing cover a little so that some light escapes the projector it will light up the reflector bowl well and make your light appear much bigger and stand out more as you will be scattering light more... but the most important part is that you wont be blinding on coming traffic.
If you are set on a brighter bulb then go with the zxe bulbs, they will get you the noticeably brighter light, just make sure you keep an extra bulb on the bike handy so that you can change it out if it goes out while riding. They are fairly easy to get to and you can easily just mount a light bulb carry box to the inside of the front fender. You'll always have a second one handy and it'll be stored out of the way and right were you need it. It's always a smart thing to store at least one extra bulb on your bike for this reason.
If you do want to go the HID route, there are plenty of cheap E-bay options, but if you want quality there are a couple threads on there about it. The ebay options will last a little while but they have a proprietary bulb that you can't just get a replacement at locally in a pinch.
The true quality option with something like the MORIMOTO MINI H1 4.1 or even the ultra mini which is conserderably smaller and very good quality. They don't require much work to install and will give you much better quality of light on the road and keep you from getting tickets for improper modification of a headlight, that blinds people on the other side of the road...
You can only put so much light out of a standard reflector housing before it's excessive and causes problems, like cops pulling you over or people constantly brighting you....