Up until now, I've been skeptical about the vast majority of aftermarket headlight bulbs for C5s.
A lot of what's on the market is junk, like–cheap bulbs which are simply a replacement 6005 or 6006 lamp but with blue glass. bulbs which are indeed very bright but have a poor design such that they glare into oncoming drivers' eyes.. Or–cheap bulbs sourced from China, Pakistan or Upper Slabovia which are a little brighter than an OE bulb burn out in a short time.
Recently, "GE Lighting." General Electric's consumer "light bulb" division introduced a new "premium" line of aftermarket automotive lighting available for 1955 V8 Corvettes and all 1956-1958 Corvettes as well as 1984-1996 Corvettes. GE named this aftermarket lighting line "Nighthawk". For Corvettes, Nighthawks are available two different ways depending on model year. They come as either LED lamps for 12-volt '55, and '56-'57s all of which have 7-inch round lamps or '84-'96s with 5x7 rectangular lamps. Also available are Nighthawk Xenon bulbs for '97-'04 C5s. Finally, there are Nighthawk Xenon bulbs available for '55-'96s which have had their sealed beam headlights replaced with aftermarket bulb-in-reflector assemblies, such as those made by Hella and Cibie. Currently, no Nighthawk upgrade is available for the '58-'82 C1/2/3 four-light system or the C6's H9 high-beam bulbs, but we suspect, if market research shows the demand is there, GE may expand the line.
Our first test of Nighthawks was to install a set of the Xenon bulbs (PN 9005 NHX/BP2 and PN 9006 NHX/BP2) into the headlamp reflector assemblies of a 2004 Z06. According to GE, these bulbs can focus up to 120% more light on the road. Because Nighthawks put out more more light than does a standard halogen bulb, you can drive a narrow, twisting road at night with an extra margin of confidence which everyone, from aggressive drivers to Sunday evening cruisers, will appreciate. A beam from a Nighthawk Xenon bulb has a sharp cutoff which may provide an increased feeling of assurance during night driving. The headlights are, also, said by GE to produce a light that is closer to daylight in its color temperature, i.e.: it's not so yellowish. A couple of technological advances are responsible for the performance gains which come from GE Nighthawk Xenon headlamp bulbs: 1) use of an ultra-fine filament and specialized coating system result in greater light output and 2) a further increase in light output come from the Xenon gas-filled bulb. Nighthawk Xenon headlamp bulbs for C5s are approved by the United States DOT and the Economic Commission for Europe.
Unfortunately, a C5 headlight bulb change is not easy when the headlamp assemblies installed on the vehicle. If the headlamp assemblies are removed, bulb changes are easier, but the task of removing the lamp assemblies is even more time consuming. As a result, we suggest you swap the bulbs with the headlamp assemblies on the car. Since it's difficult to see the installation procedure as you do it, for the most part, you work by feel.
First, temporarily remove the two hood stops which are on top of the frame rails just inboard of the headlamps. With the stops out of the way, reach though the opening and remove the bulbs, one at a time. When you do that, feel the position of the bulb connector. Remember the "feel" of its clock position when locked in place. Then, twist the bulb to unlock and remove it. With the bulb removed from the headlamp assembly, pull it to where you can see the connector then unplug the bulb from the headlamp wiring harness.
Take a Nighthawk Xenon bulb out of its packaging–keep in mind that low- and high-beam bulbs are different–plug it into the headlamp wiring harness then twist-lock the bulb into the headlamp assembly. That is the hardest part doing the swap by feel. Make sure the bulb is seated correctly in the headlamp assembly before you twist to lock it in place. When your done, replace the two hood stops. There is more information on headlamp service in the Factory Service Manual for your car's model year including instructions on how to aim the headlamps if necessary.
Before you go out at night to drive your new Nighthawks, back out of the garage, close the garage door then turn on the headlamps. If you find any light beams that are aimed way off to the side or way up or down, go back and re-seat the offending headlamp bulb because you probably only "caught" two of the bulb's three locking tabs in the headlamp assembly. If the light pattern still seems incorrect, take the car to a service facility which can aim the lights or consult the Factory Service Manual for aiming instructions.
We tested Nighthawk Xenon bulbs in our 2004 Z06 for several nights of driving. It was visually obvious that these bulbs are an improvement in lighting and, unlike cheap aftermarket bulbs, they create no problem with glare for other drivers. The light emitted by a Nighthawk Xenon bulb is a somewhat cooler white and, as advertised, seems closer to daylight color temperature. Also, the light pattern of the high-beams seems to "reach out" farther than the stock Sylvania bulbs installed on the car before our test.
We did some imaging of light patterns and, as you can see form the pictures, the Nighthawk Xenon bulbs are a visible improvement. These images were taken from the same spot on the same stretch of road on two different moonless nights. We recommend these bulbs as an upgrade for all 1997-2004 Corvettes.
For more information visit GE's Nighthawk Xenon web site.