Here is some informative and interesting information, excerpted and paraphrased, from the following Dan Stern website referred to in a previous post:
http://www.danielsternlighting.com/home.html
For those who want the best possible performance from their headlamps and are more concerned with their ability to see rather than the appearance of their headlamps, the major bulb companies offer optimized bulbs without the light-stealing blue glass. Narva RangePower+50 and RangePower+30, GE Night Hawk, and Philips Vision Plus, and Osram Silver Star are the ones to get.
A major reason why many people find many US-specification headlamps in need of upgrading is because many such headlamps have very low levels of foreground light, which creates a "black hole" on the road in front of the car. There's often insufficient lateral light (left and right) to see critters or people before they run into the road. The "hot spot" creates a narrow tunnel of light that disappears "out there somewhere", with no visual cue to where the beam (and therefore the driver's seeing range or "preview") ends. But these headlamp performance aspects are governed by the optics of the lamp, not by the color of the light. Bulbs with blue or purple tinted glass never improve the performance of your headlamps. They may leave it relatively unchanged, or they may severely reduce it, but they never improve it.
Get the longest bulb life rating you can.
Do not get blue-colored or other tinted color bulbs. They don't work as good as plain white ones.
"Superwhite" "Hyperwhite", "UltraWhite", "Platinum", etc., basically any bulb advertised as being "whiter" than normal) bulbs produce more glare and less seeing light than standard bulbs.
The "55W = 85W" (claiming you get 85W of light from a 55W bulb) type claims are a sham. Here's how these kinds of pretend wattage numbers are cooked-up: The blue or purple filtration coating on the glass tints the light so that it is "whiter". Most bulbs that actually produces more light (i.e., higher-wattage bulbs) also burn with a whiter color than standard-wattage bulbs. With these color-coated bulbs, only the light color, and not the actual light output, imitates a high-power bulb. There is no seeing advantage to "whiter" light, though some people seem to think that others will look upon headlamps so equipped and go "Wow, cool!". Why they believe anyone else cares what color their headlamps are is anybody's guess.
Discount claims that a bulb produces the whitest or brightest light of any bulb.
Ignore "color temperature" claims. They're a sham. Color Temperature is a real measure, but it is being improperly used to claim improved seeing. Color temperature has no predictive value for the performance of an automotive headlamp, nor does it indicate how well you'll be able to see.
HID lights or conversion kits are not worth it, are pricey, and may not be safe.
