Agree with SlyCoopers. The HID's looked brighter when looking at the car from the outside, but somehow appear dimmer from inside the car (where it's important). I went back to HID, though all the other bulbs are LED.
Was able to put the slim ballast (Innovited) into the headlight housing, along the high-beam bulb
The HID bulb protruded enough to not be able to put the cap on, so I used some threaded sprinkler riser tube, and also the threaded cap to accommodate and seal the housing.
Had sent this to someone else in a DM, but maybe it could be useful info.
I got these 2 years ago, still works fine
H11 (H8/H9), 5000k color (white, w/o being too blue or dim like 6000+)
In the pics you can see the ballast is stuffed in the high beam area, and the wires are easy to get to.
You DO have to drill or holesaw a hole in the low beam bulb cover, and then thread the sprinkler threaded union so it will clear the HID bulb. Stock bulbs go in an L shape, HID's are straight and will not fit unless they have a bit of clearance.
Two of these
and two of these to cap them shut
bit of silicon or caulk to keep it sealed and so it doesn't unscrew. Drill the hole a bit smaller than the threads, and you should be able to screw the threaded plastic into the light cover.
mark center of cap where you want to drill, you will have to see where the HID wires touch it, and use it as reference to drill... it's not exactly center as you can see from pics.
my caps are red, and I got the threaded stuff from ACE hardware for cheaper than amazon.