One of the biggest complaints you will hear about the S14/a is that their headlights are pitiful! There are various options you can take to partially overcome this problem. Fitting high power bulbs, 'special' white or blue bulbs, etc.
The only really effective solution is to invest in a HID (High Intensity Discharge) conversion kit. The price for a kit can vary wildly from £150 to £300. Mine cost about £150 from the US, though you have to take into account additional delivery costs on top of that. Buying several sets for other people will help reduce this. I got mine off Ebay from this seller.
Figure 1 shows one of the converters. I opted for the 4700K bulbs, as these are the closest to those fitted by car manufacturers. Other bulbs are available, but be aware that some are illegal in the UK
Remove the first headlight unit. If unsure how to do this, follow my instructions here. Remove the wiring connector, plastic dust cover and rubber seal from the outer light housing. Unhook the wire retaining clip and remove the existing bulb.
You now need to find a mounting place for the two ballast boxes. I attached mine to the base of the headlight unit using the adhesive pads supplied with my kit. I found this to be the least obtrusive location, especially if you have an FMIC. The guidelines state to mount it somewhere where it will get an air flow.
VERY CAREFULLY insert the new xenon bulb and clip it into position. It is imperative that you do not touch the bulb glass with your fingers nor catch it on the housing.
Pull the rubber grommet on the wires about an inch from the ballast. Pass the rubber seal over the ballast connectors and wires.
Now fit the rubber seal onto the housing. You should find that the inside of the seal should push tightly against the grommet and form a quite tight seal. You may wish to add additional damp-proofing around the seal and wires before screwing the dust cap back.
Join the two ballast connectors to the converter connectors. They are opposing connectors, so you can't get it wrong!
Slot the two spade connectors into the H4 adapter as show in Figure 8 and snap the back into place.
Connect the adapter to the existing H4 connector.
Made sure all the connectors are tucked in neatly behind the housing unit before fitting it back. This makes all the connections accessible.
Repeat this process for the other headlight unit.
THIS IS IMPORTANT!
When the lights are switched on for the first time, keep them on for ten minutes. This is important for the initial 'burning in' process. Also, ensure you get your alignment checked, otherwise you will find everybody flashing you to dip! If you want an accurate way to do this yourself, take a look at these guidelines.
Figure 11 shows the startling difference between the new HID xenon bulbs and the normal halogen bulbs.