Appendix “I”: Upgrade, Installing Xenon High Intensity Discharge (HID) low-beam headlight bulbs

Disclaimer: The content of this document relates to the Porsche 993 (911 1995 to 1998). I am not a professional automotive technician, and some of the opinions expressed in this document are just that, opinions; therefore, please feel free to use this document at your own risk. Many times, a lot can be learned by simply watching qualified professionals work on your 993

Appendix “I”:

Several years ago, I updated my existing low-beam bulbs with a 6000-degree Kelvin HID Xenon kit designed for replacing the H-1 halogen bulb in our cars. Most of the aftermarket generic kits are very similar. 

To do a minimally invasive job, you will need a generic kit for H-1-style low-beam bulbs with “slim” or smaller ballasts. With a bit of Do-It-Yourself engineering, the installation is relatively easy, as all the components will fit inside the lamp housing and is completely reversible. 

12/10/2025 The 993 dedicated kits offered by Tore from www.bergvillfx.com had a nice bracket to hold the ballast inside the pod. Unfortunately, these kits are presently unavailable. Check here for an update on availibility.

The high-voltage wires that come with the generic kits are designed for multiple application fitments and are longer than needed for a 993. The longer wires must be bundled in the housing. Some recommend against shortening these wires, as any voltage leakage from reinsulating them may prevent the bulbs from igniting. Others have shortened them with good success. 

 In any event, do a bench test of any unmodified or wire-modified system by trial-firing up the lamps before installing them. With the long wires, the installation does not look too neat inside the housing, but it has been working reliably in my case since 2008.

In the kit I used, the 12-volt electrical wire terminals leading to the original halogen bulb could be used to connect the HID system. No cutting or splicing.

Headlight Pod

Headlight Lens
In Frame

While the lamp pods are out, consider cleaning the reflectors and the inside of the glass face lenses. If the glass lenses have never been removed, the clips surrounding them are factory-melted and fused to their pod body.

Headlight Pod
Clip Location

The fused section can be ground off with a Moto-Tool or cut loose with a utility knife. The clips can be brittle, so one or more may crack when releasing them. This isn't a big issue, as the glass lens appears to hold on well with a cracked clip or two. When reassembling, there is no need to remelt the clips; they hold on just fine by spring action as is. 

If you decide to clean the mirrored reflector, use a very soft and clean microfiber cloth, such as one used to clean eyeglasses, as it is easily scratched. I also recently came across a chrome paint maker that may be useful in touching up the mirror-like reflective coating inside the headlight pod. I have not tried this product, but it seems promising for repairing mirror reflective coatings on glass or plastic. I would test it first and evaluate the results before trying it on a lens pod reflector.

https://www.arromark.com/manufactured-product-lines/flomaster-mirror-finish

Also, there are services that rechrome plastic parts that can produce a mirror-like OE finish.

I hear all sorts of discussions about needing a larger fuse for the 35W HID bulbs because the system is supposedly hard on the existing power switches during initial loading to ignite the bulbs. I did not choose to address this issue in my installation because, in my understanding, switch wear comes from the spark during the transition to open (off), not during the transition to close (on). In other words, a switch can withstand a lot more load on close than on open. When the plasma-based lights are turned from on to off, they are lit and warm, so the load and therefore the stress on the switch is lower than with the original 55-watt H1 halogen incandescent lamps. This lower demand should render the need for a more robust powering circuit moot. (7/10/2021) -- Now that the aftermarket xenon bulbs have been in my daily driver for 13 years, I have not experienced any reliability problems with the headlights.

Special care should be used when aiming the headlights after the installation. I used the USA DOT aiming procedure that can be found on several websites. When I did this, I found that oncoming cars would flash me, thinking my headlights were on high beam. Blinding opposing traffic probably cancels out any safety advantage of brighter daylight-color bulbs. I lowered the aim of my headlights slightly below the DOT specification, and other drivers stopped flashing me. Here is a page that discusses aiming headlights once an HID kit has been installed.

Making the High-Beam & Foglights color match the HID headlamps:

If you installed 6000 Degree Kelvin HID bulbs (daylight color) and wish for your high-beams to match in color, they do make replacement halogen bulbs with blue-tinted glass envelopes that can provide a good color match. This also goes for the fog light bulbs. 

Here are the gotchas on this job.
1) Regardless of the brand, many times HID bulbs/ballast kits are Dead On Arrival (DOA) out of the box, and so should be powered up, bench-tested, and proven to function before you install the components in your car.

2) The way HID lamps work is that a very short 18,000 to 35,000-volt spike (trigger) is sent to the bulb that causes the gas in the bulb to form a plasma and ignite. Then the supplied voltage drops back down to 85 Volts, sustaining the plasma state. For this reason, bulbs may not ignite reliably if any electrical grounding leak issues on the bulb or its feed wires diminish the initial pulse. This means any dust, dirt, or moisture inside the headlight pod should be cleaned out before installing the bulbs. Also, brand new bulbs will sometimes not light up on powering up every time, so cycle the headlight switch again to light them off and run your headlights for a short burn-in period to season them before concluding that something is wrong with your setup.

3) The H-1 compatible xenon bulbs that come with the HID kits sometimes have a slightly oversized glass envelope diameter, making it difficult to slide easily into the bulb socket. I had this issue and just reamed out the socket diameter very slightly with a mini-grinder to allow the bulb to fit.

Dremel Mini-Grinder

This doesn't damage the socket or make it incompatible with an original H-1 Halogen bulb or its HID replacement. Some have suggested that this issue may only appear with earlier production cars. If you do end up reaming out the socket, some suggest holding the lamp pod with the pod housing back facing down so any debris created from reaming falls out of the fixture rather than into it. In any event, be sure to vacuum up the dust & debris it creates to avoid it from interfering with the bulb's ignition.

4) Getting the headlight pod back in and the electrical plug lined up can be tricky. Spray some Teflon or Silicone lube on the headlight pod's mounting tracks, and the pods should slide right in. Also, rub some of the lube with your fingertip around the edges of the electrical socket to help it fully seat.

7/2025 A recent posting on Rennlist related to the new LED bulbs:

StevenGilroy

"These [LED headlight Lamps] have ballasts and are fan-cooled, they work well, super bright, but the light control is not precise so a huge area is illuminated not good in rain or mist. [The result of the optical system being incompatible with the layout of the LED bulb.] Two friends bought LED without ballasts or heat sink/fans and they overheated after a few minutes, one melted the plastic of the headlight unit the other just died. The bases also need a heat isolator, most have a silicone rubber ring that adapts the universal bulb to the H-1 diameter, this allows the fan to cool without heat transfer to the headlight bucket."

09/07/2025 A recent Rennlist posing by member pzi993 concerning replacing a failed ballast on the Bergvill F/X low beam HID Kit:

(pzi993) I replaced both ballasts with Amazon variety DXNQ-3920XH - [url]https://www.amazon.com/dp/B0DN16B42W[/url] for $15. I reused Bergvill F/X [12 Volt] ballast supply wires by cutting them off the old ballasts and soldering them to the new ballast's wires. The replacements come with the separate igniter boxes, so packing them into the 993 headlight compartment posed some challenges, but it worked ok.

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