[I'm still trying to install 9004 Base p29t, bi-xenon bulbs in my 1993 XJS. You would think "drop-in" but not so.
The first problem encountered was the three alignment tabs that locates the bulb properly were missing on the right headlight. That lamp rotated 360 degrees. The left one found the tabs immediately. But!
This creates a second problem. The bi-xenon bulb changes location when the beam is changed. On the filament 9004 bulb the filaments are horizontal and don't move. On the bi-xenon bulb when in the tabs, the bulb moves down or up at a 45 degree angle. Since it doesn't conform to the filament bulb but is in the tabs, should it move at a 45 degree angle or move up and down or left and right? To complicate the problem further when it moves is it in high beam or low beam?

For those that are not aware, the movement of the bulb is by magnet engaged by one unused light socket and then to the red and black pair that goes to the bulbs. There is another system that partially retracts the bulb into the bulb case.

UPDATE:
From a professional source I have been told to center the bulb and have the bulb move up and down. In the relaxed position it will be on low beam,
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you are converting it to HID? The lamps in your XJS are not designed to throw those lights and will blind people unless you point them at the ground, in which case you aren't seeing any further than when you started. Just buy some premium halogens that are close to daylight/white.

 

I understand your concern for other drivers. I have the same concern. I intend to put a metal ring around the bulb extending to the end of the bulb. From the gas bubble to the end of the glass remove about 3/4 of the top of the metal circle. This is a very simple modification that I have made in about 15 minutes
This should remove light being reflected from the bottom of the reflector into the oncoming traffic and thus satisfying your concerns. It will also increase the forward light three fold over a halogen bulb.
Before I take the car on the road I will check beam pattern 25 feet from the alignment patterns I have made.

 

Can you explain how you can make a light brighter, thus lighting up more of the road, without it appear brighter to the people/cars on the other side? I understand the stock lights are limiting, but I feel like most HID conversions are made to be as bright as possible, not necessarily matching new stock cars, which have improved distance over old cars.
Personally I would use LEDs if I was trying to fab some conversion, but w/e I need to re-coat the inside of my lights before doing anything anyways..

Engaged is supposed to be high.
Look at your old bulbs. Is the high beam filament offset from the low? If so, you want the xenon going in the same direction.

 

Your response is noted.

 

Somewhat relevant to the original post, I ask the following:
On my 1992 there are horizontal and vertical "alignment" adjustment screws on the inside of each front fender in the engine compartment. Are these indeed functional for the 92 Eurolights ? or are they a holdover from quad lights and therefore they don't work ?
Any help etc...greatfully received and applied...

 

I did fit LED headlights to my '89 and found the dip would not work. Tested the fitment and function after swapping out one side first and all was good but after swapping out both sides would not change high to low. Not sure if it was due to low current draw but l did not think the result was worth the effort and went back to original setup.

 

On this original post I was talking about inexpensive Chinese bulb. I subsequently change to Kensun kit bulbs. still Chinese but better quality. These bulbs retract rather then changing angle. As a result you don't have to concern yourself on placement into the lens.
To answer the question about alignment I have not taken the lamps apart, but I assume if you keep the OEM lens or its carrier, if there is one, then you can adjust the beam pattern. Just try to adjust them. You will soon know!
I can tell you this: the lights are bright and the road is illuminated well. I seldom ,if ever, get flashes from on coming driver. I attribute this to proper alignment of the lights.