I notice that many people in this community use the Sylvania Silverstars and love them. If so, please disregard this post and continue enjoying your product.
However, if you truly want BRIGHTER light, not just WHITER/BLUER light, please read these two links.
Link 1
Link 2
Before I got my HIDs I was probably on the same boat as a lot of you. I felt the KJ's headlamps had good dispersion, but it couldn't hurt to make it better with brighter and bluer light. I went through 3 different sets of bulbs before I finally decided to drop the idea altogether and just go with what I had wanted all along --a TRUE HID system.
I first picked up the Silverstars. Brighter light (or so it seemed until about a month) and definitely more white. The high price doesn't justify the perceived benefit however.
Next was a pair of Nokya 110watt 8000k (8000K should actually be deep blue, not slightly purple) looking bulbs. I've heard that higher wattage bulbs provide more light output but can strain the electrical system. Its a Jeep anyway and I figure it could handle the extra load. It did, but I still wasnt happy with the light output because the deep purple filter on the bulb negated the effects of the extra wattage, and also because the higher up the Kelvin color temperature scale you go with your bulbs, the less usable light you will get. Even with a true HID system, the blue or purplish color might look really really cool (I was definitely a sucker for the color aspect), but if you research it, a lighting system closer to about 4300K-5000K will provide the most lumens. The higher on the scale you go, the more color you will get at the expense of usuable light. Lighting closer to 3000k will be very yellow and cut through fog (lower color temperatures have the best distance, hence why its easier to see stopsigns and red lights from far away than green lights), but you probably wouldn't like this color unless it was just for fog beams, or if you had 3000k HIDs.
After I got tired of the faint purple color, I went to 55watt Litech 5000k looking bulbs. The usuable light output got whiter again and definitely more blue than the silverstars, but alas it wasn't actually any brighter than the stock bulbs.
So after spending roughly $100 on crappy HID imitation bulbs, I took the plunge and ordered my 6000K HID kit. Best investment for my KJ I've made so far (AEM intake would be next). While the existing headlamp housings weren't designed for HID specifically, the lighting was definitely FAR FAR brighter.
After driving with HID for a while however, I now wish I had ordered a 5000K kit instead of 6000K. The reason being is that when driving in certain areas where the pavement isn't as reflective (depends on the grade of the asphalt I guess), the color temperature of the light blends in with the pavement color making certain things not as visible as they otherwise should be. A shift to the more-yellow, less-blue output of 5000K provides more illumination in those difficult areas and is also actually a lot easier on the eyes (of the driver, not oncoming traffic), which is what an HID system should achieve in the first place. I don't know who's ridden in a vehicle equipped with 8000K (deep blue) HIDs or higher (such as 10,000K and 12,000 show car only systems), but if you do, you will notice that there is just a lot more color on the road and not much usable driving light. Sure it looks cool, but the HID system is supposed to help you see, and not BE seen.
Although it is illegal to convert a halogen lighting system to HID because of optics concerns about focus and cutoff pattern, a true HID system is light years better than all the crappy lighting products that these unscrupulous companies are trying to sell you. You can always fabricate a projector system into the KJs housing (which I want to hear about when someone in this community actually does), and if you're even more crafty, you can fit a self-levelling (projector adjusts aim according when nose of vehicle is pointed up or down like on a hill) projector housing.
Many will argue that it is dangerous to other motorists if you are using HID in a vehicle not meant for it. In my experience, oncoming traffic will be able to see you a lot sooner and will take steps to avoid being blinded by your light, meaning they will have to be more aware of their own driving. This is okay with me since there seem to be too many people who aren't concentrating on that task while at least one of their hands is holding a steering wheel. If my massively bright lights dont make them focus on getting out of my way, at least I'll be able to see them before I run them over (j/k).
If you are considering upgrading to HID, remember these details to make sure you dont get duped:
1. HID systems run at a LOWER wattage than normal halogens (35watts versus 55watts)
2. It's not an HID system unless there is a ballast to be installed with it (sometimes a separate igniter too), AND
3. HID bulbs DO NOT use a filament (they operate similar to a neon sign where light is generated by a pocket of gas)
Bulbmakers will try to sell you all sorts of bulbs in different colors with different kinds of gases they claim to have in them. You'll see everything from "Hiper/Hyper white" to "Plazma/Plasma" "Xenon" "Krytpon," et cetera. It's all a gimmick to sell you an inferior bulb with no greater output than your stock lights.
There are a few rare exceptions however.
Both of the links say that SYLVANIA Silverstars are a DIFFERENT product than OSRAM Silver Stars.
Osram is a German company that bought the American Sylvania and both their products are still sold. Apparently the Osram bulbs use a perfectly clear glass while the Sylvania bulbs use a mostly clear glass with a slight bluish/purplish tint to it. The logic is that since the Sylvania bulb has that slight filter, it is absorbing more of the yellow spectrum of light and outputting only whiter light --which is actually minutely less light output than stock bulbs. The Osram bulbs supposedly work better because the filament used in them is more efficient, which leads to slightly better light output than the Sylvania product. (1000lumens for Sylvania versus 1150 for the Osram if I'm not mistaken)
I hope this information has provided useful to some of you. I felt like this is much needed information seeing as how this is a Jeep community and a lot of you like to go to VERY VERY dark places in the middle of nowhere.
I however, drive in the mountains on well paved roads.
We all could use better light.
EDITED
Here's a diagram I drew of connecting an HID system. And following it is a picture of the kit of the same brand as mine (the harness shown in that pic may differ from the actual harness given). I guess the guy I ordered it from included the wrong harness by accident, so it wasn't too much trouble for me to splice wires (my setup is identical to the bottom diagram).
Keep in mind that when you cut the original connector off the main leads for the headlights, if for some reason your HID bulbs burn out prematurely (which is not likely but sometimes can happen) [HID bulbs should last the life of your car], you will have to splice the original connector back to the wires to be able to use the standard 9007 55watt bulbs. HID bulbs have beefy wires extending out the back to connect directly to the ballast or igniter, and will not fit on the 55watt bulb harness.
Oh yes, the actual installation:
1. In my case, I had to cut the harness off the main leads (but if you get the right plug and play harness you wont have to)
2. The ballast mounts to something solid and flat with industrial double sided foam tape (clean the mounting surface with alcohol), or you can always fabricate a bracket (then drilling might be involved)
3. If you get the right bulb size for the KJ (9007 with straight connector), it will fit perfectly in the lamp housing (some people will modify a similar bulb type such as a 9004 by cutting off some of the plastic tabs and fitting that way)
4. You'll have an abundance of wires when finished, so be a good Jeeper and zip-tie the bundles afterward.
**Coming soon** : pictures of HID beam spread
EDITED
Here's pics of the beam spread. It might look the same as the stock lamps, but I couldnt really show you a side by side comparison because I didnt do a before and after set of pics. The sides are a lot more illuminated, and the front throw is greatly improved. I had to aim the lamps down a bit from the original focus because the light was so intense that it blinded a lot of cars. With this aim, it blinds only slammed honda civics and miatas.
EDITED
Here's a video of driving with it.
http://www.youtube.com/watch?v=dKocZngFFvQ