I have a 2002 VW GTI 337 and i really want to upgrade my headlights to xenon, but i have no clue if i have to buy a complete new headlight assembly or if i can just buy xenon bulbs and slap 'em in. Suggestions, thoughts?
You would almost certainly need a new headlight assembly – xenon lights require ballast (similar to household fluorescents) and leveling equipment. There are no such things as xenon bulbs; anything advertised as such is lying.
Yea, looks like youre right. Heres a link where “high intensity halogen” is billed as xenon:
http://www.buytruckstuff.com/s_product_gp.asp?selcategory=25
So, whats “leveling equipment?” Also, what is HID an acronym for?
High Intensity Discharge.
GE (who makes them) would seem to disagree with you.
“Leveling equipment” is basically an electronic or mechanical device to keep the very bright beam of the xenon lamp pointed down to the road surface rather than in the eyes of oncoming drivers. This is especially important, for example, when the road ahead of you falls away (e.g. when cresting a hill), or when you’re tail heavy, causing your front end to point upward.
The leveling equipment is designed to correct for a tail heavy condition such as a full trunk, or towing a trailer. This is a legal requirement for HID lights in the US
The leveling system has no clue what the road in front of the car is going to do, so it can’t correct for the car cresting a hill.
Interesting. So, why wouldnt high intesity halogens need the same type of equipment?
Oh and I can assure you that the HID lights on my car do have bulbs. We take them out in class.
I think what 3waygeek was trying to get across was that there is no drop in replacement bulb to make existing headlight assemblies into HID lights.
Ah, that could be. There are conversion kits though, which include levelling equipment, ballasts and what all.
Q.E.D. – this thread refers to automotive headlights; your link doesn’t. The OP specifically mentions “xenon bulbs”, which in that context are a scam – they’re basically regular incandescent or halogen bulbs with a bluish tint to make them look like genuine HID lights. I see on preview that Rick understood my point; perhaps I didn’t explain it quite thoroughly enough in my initial post. Anyway, between the three of us, I think we’ve covered this sufficiently for the OP’s purposes.
Homercles – my understanding is that “high-intensity” halogens aren’t as high intensity as HIDs.
Any linkage for where i might find such a kit? 
Here is one.
I don’t think this is true for the US. Can you provide a cite for that requirement?
Other than my company’s internal New car features training documents that said that such leveling equipment was a legal requirement, no I can’t.
WHOA! Stage I: $1699.99. Stage II: $1999.99! Guess i will have to hold off on this idea. Thanks for the help guys. 
Well, I was only asking because I know it’s a requirement in some other parts of the world, but not the US. I searched the US Federal Motor Vehicle Safety Standards and could not find such a requirement.
::: shrugs:::
Could have been a mistake in our docs.
There are better bulbs that will give you better vision at night, one that I remember actually has a slight yellow tint, it doesn’t amke it look modern but it more then does the job. Also the europian bulbs/headlight assemblies (non-HID) are superior to US DOT setups but technically can fail your inspection
Here in the New York area, the theft of Zenon lighting systems is rampant…more so than airbags in the past… I believe the Nissan Maxima is a prime target, as all it takes is a screwdriver. A lot of less skilled crooks are tearing up the hoods just to get into the headlight area. Local police have advised to park headfirst up against a wall if possible. Ah, the good ole days when all they took was your battery.