My '04 SVT/Euro came with the factory HIDs, and they are excellent. They are super bright, are very easy to aim, and have a motorized shield that allows use of the low beam HID when the high beam HIDs are in use. Functionally, I believe they are superior to any reflector type light. Because I don't particularly care for the busy look of those HIDs, a year or so ago, I installed a pair of ST170 reflector type headlights, with these http://store.candlepower.com/osraulhiouh7.html
Osram Rallye 65w ultra high output bulbs. The ST170s look fantastic, (probably the best looking head light you can put on a Mk1 Focus) gave excellent out put, nice beam pattern, but they were not as bright, and did not reach as far as the HIDs on high beam. Finally, I purchased a pair of new Hella HIDs http://forums.focaljet.com/new-produ...light-buy.html
from Perfect Circle Auto Parts on FJ. They perform within a whisker of the stock HIDs. Low beam (HID) performance is equal to the stock HIDs, high beams are reflector type, and with the Osram Rallyes, are excellent, although not as good as the stockers. However, IMO, they look many times better. As you are probably aware, all of these are expensive, but far superior to the standard Focus reflector head lights.