IMO, aftermarket xenons aren't as good as OEM... why? cuz they're usually closer to blue than yellow. And YES, the more blue the light, the worse it is for actual usage.
Check out www.danielsternlighting.com for a lot of useful info.
I found this site just in time, since I was planning to upgrade the lights on my E34 to xenons. I ended up with a full Osram halogen upgrade instead... Silverstars for my main beams, and All-weather for my fogs.![]()