After 18 years, it's time to polished the headlights the easy way -by taking them out (jk). My HID headlight output has been gradually getting worst (kinda dangerous actually). D2S bulbs don't blow like halogens, instead they emit less light as they age.
The motivation was really to replace the bulbs but the OM says you are not suppose to replace the bulb yourself...

. You absolutely can but it involves taking of the bumper cover and removing the headlights to access the servo/bulb; dealerships want to bill you for that.
FWIW, I shopped AliExpress for Phillips D2S bulbs (more half the cost) and while the seller listed a 'generic' pic of the box without the word 'PHILIPS', the actual product does and the base is etch Made in Germany. Given the overall quality (looks&feels good), my SWAG says they source the base from Philips but add their own filament/gas/glass -or it's a good counterfeit, time will tell. I do feel these are not as bright as OEM (based on memory b/c I recalled being WOW'd by OE HIDs, it was better than friend's cars with HIDs at the time) but I also did poor job in polishing the cover to get it crystal clear so I know I'm loosing some output. Overall it was a cheap DIY but for anyone who cars to keep their car, I recommend buying replacement headlight covers (they are cheap) to get 100% crystal clear lens.