Why is it that the dealership tells me that I can't add OEM HID after the car has already been fitted with halogen? I would like to be able to swap out my entire housing for the HID housing.

I have installed XD HID kit but am not 100% satisfied with the beam pattern. It's fine but just not the same as OEM. I would like more light to the sides...etc.

The factory HID housing is different because it's made to fit the D4S bulbs and if you didn't get the factory HID option then it's just a standard H11 bulb. Both bulbs has totally different retaining thingy around the bulb to hold it in place of the housing. If you want the OEM HID then you would have to buy different pair of headlamp to fit D4S.

Might be able to find a set on ebay, or a junk yard somewhere...

I dont think you understand what i mean. I may not have explained it clearly. I want to replace the entire lighting assembly on my halogen fitted car with one that has autoleveling/AFS/HID...

Is that possible? Could I go to the dealership and buy it and install it?

I have never heard of anyone doing the auto-leveling HID kit aftermarket.

its possible but very costly. i remember someone mentioning this in the thread but its costly to put sensors all over your car not to mention program it in a computer in order to get the AFS. the best solution is to simply sell the car or stick with the aftermarket kit. seriously there isnt a drastic difference between the OEM and aftermarket. sure you get the cool AFS but i dont think its 100% of a better lighting system if you have it. most driving is straight anyways not taking turns like you are michael schumaker.

Oh all the sensors do not reside in the assembly? You're right I dont drive like Schumacher but I do drive like Senna...hahaha. That's too bad that I can't do this...if I had bought the car new I would've got it with OEM HID. Oh well.

Save some money and go with Aftermarket, very cost effective and a easy install. no dealing with the dealership what so ever. Many people here have done it. I personally have also, i didn't do the drilling of the hole on the back cover of the headlight and still have no condensation, only thing i did was plug and play then duck tape over the cover. I figured if it did start to condense i'd just throw the regular H11 bulbs back in and restore the black recovers to their original spot. No sign of any fiddling around by me, and free headlights from Lexus hopefully. I searched and you can't buy the back covers to the headlights separately from the actual headlight.

I was in the similiar situation like you, I wanted the OEM HID because of the beam pattern and cut off. I asked sewell lexus and they said that I am better off buying a 2IS already equipped with HID. Well, I'm still determined to get the OEM HID, so I bought the OEM 2IS HID projectors and the ballasts from this guy on ebay for very cheap, and I am about to retrofit them onto my headlights. I am also swapping the lens with the FX35 clear lens to give it a sharper cutoff and trying to position the projectors out more so it will hopefully make the beam wider. When I do start on the project I will try to post some pics on how I did it. But the only thing is that I won't have AFS, but its ok I can live without it.

This is true. Cars without HID simply are not wired to have OEM type HID/AFS/Auto-leveling headlights installed. How would you wire up steering input for AFS? The factory HID option is so integrated into the car that to convert standard to HID would be near impossible.

Oh sorry, I was just trying to answer your question on why you can't use OEM HID with halogen headlamps but yup like everyone said, it would be costly and better buying one that is equipped.

RedLexin - you can purchase the back covers to the headlights...ive bought 2 sets already from my dealership. there is an actual part number and everything...i have it somewhere if you need it, let me know!

I'd suggest you go with the retrofit route. It'd be cheaper than replacing the whole headlight assembly. Plus you will get the OEM look and beam pattern that you wanted.

http://www.customlightz.com/