Retrofitting OEM HID Projectors into Honda and Acura Headlights

Start with a projector that was designed for a xenon arc, not a halogen filament. Do not drop D2S bulbs and ballasts into the factory halogen projector or a reflector housing; that pairing sprays light everywhere and blinds oncoming traffic. Within the Honda community, S2000 and Acura TSX projector units are common donors, while BMW E46/E55, Audi A6, and Mercedes SL500 optics are also used successfully. Before committing, confirm the projector body and its rear collar will physically clear the depth of your chosen headlight housing.

Warm the seam of the housing to soften the factory butyl sealant, then separate the outer lens from the reflector bowl. Inspect the inner lens surface. Integra-style lenses carry molded flutes or textured ribs that smear a projector's crisp cutoff into a wavy double-arc and rob it of output. Where the texturing sits directly ahead of the projector, sand and polish that patch smooth, or fit a clear fluteless lens; leave the texture in front of the fog and corner sections alone.

Cut an opening in the reflector just large enough to seat the projector body, then fabricate a bracket that locks the unit solidly in place. Position it so the D2S arc capsule sits where the original H4 low-beam filament used to be; nailing this location is what keeps the beam even and aimable. Compact housings surrender some aiming travel, so take the time to get the projector dead level before you bond anything.

Wrap a glare shield or shroud around the projector so light cannot leak past the lens edge or bounce off the surrounding reflector. Escaped light reflecting inside a reflector-based housing is the single biggest cause of glare in a retrofit. Where the housing has a large bright bezel below the projector, such as the chrome area on 98-01 Integra lights, paint it flat black to kill those reflections.

Add a removable rear cap so the D2S connector stays sealed inside the housing yet can still be reached for bulb changes. One documented approach bonds a Hyundai Sonata cap to the stock rear piece with epoxy while keeping the factory rubber seal to maintain the weather barrier. Caps taken from JDM Integra Type R headlights, or from USDM 1994-1997 Accord headlights, are reported to fit with far less fabrication. Once sealed, re-bond the lens to the housing with fresh sealant.

Mount each ballast and ignitor in a protected, weatherproof spot; one build placed Philips LVQ-212 ballasts in sealed cases under the bumper beam. Build a relay harness that powers the ballasts straight from the battery through one 30A relay per side, triggered by the factory low-beam circuit, so the original headlight wiring is never asked to carry ballast load. Install the chosen bulbs, for example Philips 85122 4300K D2S units.

Face the car at a flat wall and confirm the cutoff line is level and consistent on both sides. Then stand in front of the car and verify no bright light spills above the cutoff toward where oncoming drivers would sit. Avoid high-wattage 50W ballasts: they add little usable vision, shorten bulb life, and create such an extreme contrast between lit and unlit zones that dark areas and road signs effectively disappear.

If the outer lens is hazed or scratched, wetsand it progressively through 1000, 1200, 1500, then 2000 grit, using water solely to flush away the removed material and keep the paper from clogging, then machine-buff with polish to bring back clarity. Be aware that sanding strips whatever factory UV coating the lens had, so treated Honda and Acura lenses can begin to yellow within a few months afterward.