I am the proud owner of a 1992 SC400. I just wanted to pass along some info to those of you who are wanting to upgrade your headlights. I just replaced the stock 9005/9006 bulbs in my SC400 with two 9011/HIR1 high-beam bulbs and two 9012/HIR2 low-beam bulbs which I purchased off of the internet. Here is a link which gives specs of 9005/9006 vs. 9011/9012 bulbs:
http://bmwz.org/articles/lighting/0506trick/
Also I have read that Lexus installed headlight bulbs at the factory with a slightly lower wattage (51 watts or something?) for increased bulb life or other similar reason; this means the difference between the new HIR bulbs and what is probably in your Lexus now will be even greater than what the above article cites.
I can say that with the new bulbs installed lighting is vastly improved. On low beams you can really see the sharp cutoff the projector housings provide. There is just a nice blanket of white light illuminating the roadway directly in front of the vehicle with no glare present from above the cutoff line. One really has to exercise caution/prudence with the high beams, but when you can find a deserted stretch of road in the middle of the night you will find that they really light up your path.
For a grand total of about $160.00 and 2hrs time I feel that this is a very worthwhile upgrade.