I installed a generic plug'n'play H4 Bi-Xenon kit into my '94 Townace yesterday. The lamps had to be adjusted slightly lower, and on the test run no one flashed their high beams at me while I drove down the busy highlevel road, so I'm taking that as a positive sign. On roads where I usually use the high beam, the low beam's illumination was more than sufficient; the horizontal coverage lit up pedestrians and bikes on the left of the road quite brightly, and the forward reach is great. The only reason to use high beams would be to flash another driver or to get a good look at the people inside the car coming at you. The bulbs are 4300K, which are the brightest you can get, short of going for the Euro style 3000Ks. Our 121 came fitted with 6000Ks (after market kit installed in Japan), and I thought they were the bomb, but 4300Ks are just so much easier on the eyes. The ballasts and igniters (two per side) were mounted inside the van, next to the rubber stopper through which the existing forward lamp harness exit, and the new wires were routed through an extra opening made in this stopper. The control box with the relay was mounted on the floor behind the steering column, which allows easy reach for a good grounding point, and a power source from the dashboard. The kit utilizes one connection from the existing harness to detect high/low signal, but power is supplied independent of the stock wiring harness. It's a fairly straight forward installation, but tedious; the side indicators and grill come off first, followed by the lamp mounting brackets on either side, on which are mounted a headlamp and park lamp. This was because I had to scout for a suitable mount point for the ballast, and it's so much easier to navigate a drill machine from the outside. I used the supplied mounting plate as a brace from the outside which will keep things nice and snug. The igniters were mounted using industrial strength 3M double sided tape. Bulb installation is straight forward too, and the bulbs themselves can be twisted off the H4 flange, which makes replacing bulbs a breeze since you don't have to deal with those finicky dust covers. I won an auction for the kit on ebay, and paid $62 + free S&H. It got held up at the EMS office, and I paid LKR1300 to clear it. All in all, the built quality of the kit is pretty good, the ballasts are the smaller slim solid state dealies, which look and weigh like solid chunks of aluminium.
One word of advice though, don't go for anything over 6000K. The reason is that, while the intensity of the colour is still high (the bluest blue possible, etc), they're not bright, and you'll have trouble focussing on objects on the road. 8000K is the absolute maximum you should consider, and that only for driving in illuminated areas on the city where you're not completely dependant on your vehicular lights. Anything higher is absurdly obtuse to derive any usable function out of, and are suited for show only (which constitutes 95% of the HID users in Colombo "omg machn thos r SO KOOOLLLL!!111 hw mch???").
Hope the details were useful.