chrisngrod said:Was it just an HID kit or something made specifically for the Lotus?
Contrary to belief there is at least one retailer stateside that will sell you a HID kit.
For the 55W marked segment, sorted in order of brightness:
+50%: Philips Vision Plus (achieves its extra performance by increased luminance, not lumens. See this article: http://www.eur.lighting.philips.com/press/automotive/resultsVision.shtml
+30%: Philips Premium, Osram Silverstar (European marked only - see note below)
+20%: Osram/Sylvania Xtra Vision, Osram/Sylvania Silverstar (North american market only - see note below)
+0%: Philips Bluevison, Osram/Sylvania Cool Blue, Osram/Sylvania Halogen Plus, and OEM bulbs like GE.
-10%: PIAA Superwite
Silverstar: Do not confuse the European (clear glass) Silverstar with the North american (slightly blue tinted) Silverstar. The blue tint steals light!
PIAA "Xtreme White" was released ~Dec 2001. No independant tests have been conducted so far, but several positive indications has it that this can end up in the +20-30%.
Note that many cars sold after year 2000 already have premium bulbs installed and therefore buying any of the above bulbs might not give any or only minor improvement. Among H7 applications, there should be hard to find non-premium bulbs.
If your car is set up for higher wattage bulbs, Philips Rally bulbs will give more lumens than most asian overwatts. Be aware that lifetime of a Philips Rally bulb is ~100hours - so keep some spares in the glove compartment.
Narva bulbs are also top notch. Narva is a daughter company of Philips with one intention: compete with top notch products on the aftermarked. Philips themself are OEM oriented.