Thanks John.
All IS300 came with factory fit HIDs/xenons, (along with the IS200 version of the ltd ed), so can't help you there. I know there is also a cover under the bulb to alter the beam pattern to cut dazzle. Basically if you look at the headlights head on when they are switched on the bottom third or so of the reflector is in darkness. You can see what I mean in the third pic.
I replaced the sidelights with LEDs along with all the interior and boot lights. The sidelights are 9LED 501 bulbs, The map and boot lights are 12LED panels, The main interior light is a 24LED panel and the visor lights are 3LED bulbs. I also replaced the front and rear indicators with silvervision bulbs.
I can pop up some pics of the headlight bulb cover and the LED panels if you want them. :)
Cheers
Dave.