The Catz Zeta kit that I use for my halogens in my E30 I bought off Ebay last year. I think they are pretty rare now. The reason is that Catz was shifting their US focus to the HID kits, and phasing out the halogen realted stuff. But when after market HID kits became illegal, I think they withdrew alot from the US market, maybe only fog lights now. I have a pair of the H4 inline ballasts that are plug and play, not necessary to go throught the fuse box, like on the newer models. It pops up on Ebay once in blue moon but less so these days.

No I wouldn't say that the PIAA Xtreme White 85 watts in H3 are brighter than the Narva 130 watt bulbs. I felt more comfortable with 85 than with going higher. And I have had really good experience with PIAA's Xtreme White product line.

No I didn't relay up the W124 HID setup
I just mounted the ballasts to the back of the headlight units and after changing the wiring harness to the Euro one, just plugged the HID into the headlight harness. I may steal the one out of my E30 to put into the W124 for the HID, but I'm in no rush right now.

I'll put a few pictures of how the HID conversion looks when I get off my lazy butt and download the pics off the digital camera memory card.

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1991 W124 300e 4-MATIC