Silverstar and PIAA
I have spent some money on PIAA H4 bulbs in the past and found they combine high price with short life. No more. Although I have always been very skeptical of the exaggerated claims of the bulb manufacturers, I decided to buy a pair of Silverstar 9006's for the foglights in my '01 C320. Unlike the high mounted fogs in my previous W202, (and 123 and 201's) the W203 fogs are small in diameter and mounted at the bottom of the spoiler and as a result put very little light out where you want it. But, much to my amazement, the Silverstars, rated at 55W just like the originals, are noticeably brighter and very white. Despite their cost, I think there is quite an improvement. I am satisfied.
I also just installed a pair of 70W H7s in the high beams. I had intended to increase the fuse size but find that all exterior lighting is "electronically fused." So, I'll just have to see if the circuit breaker notices the extra amperage. Or not. BTW, I bought the H7s from JC Whitney, three for nineteen bucks. Such a deal. They sell several variations of H7s.
An ongoing research project (so far) is to convert my Xenon headllghts to the 2003 Bi-Xenons. This won't be cheap, at about $1500 for the two assemblies, but I can't find out if the wiring harnesses and plugs are the same. No one at the dealer knows and even examining the parts microfiche is not much help. I need to corner the factory rep but haven't seen him of late. This will take longer that I anticipated.