If you are unhappy with the headlights on your Alfa 156, you can upgrade them yourself to High Intensity Discharge (HID) aftermarket headlights. HID headlights emit more light, last longer and use less energy than the factory-installed halogen headlights fitted on the Alfa 156. The downside is that they are expensive: a pair costs about 100 dollars, although this price includes all the hardware needed to put the HID headlights in. Expect the process to take about 30 minutes total.
Turn off the Alfa 156 if it was on. Prop open the bonnet with the bonnet support rods.
Press in on the side tabs of the headlight wiring harness. Pull out the headlight wiring harness.
Pull off the weather rubber shroud from the rear of the headlight assembly.
Put on your latex gloves. Press in on the retaining clip holding the headlight bulb in place. Pull out the headlight bulb. Store for reuse or resale.
Mount the ballast that comes in the HID installation kit to the rear of the headlight assembly with the double-sided adhesive tape or the zip ties that also come in the kit.
Secure the HID headlight into the headlight assembly with the retaining clip. Cover it with the rubber shroud. Thread the socket on the rear of the HID headlight through the hole in the rubber shroud. Plug the headlight wiring harness that you removed earlier into the ballast. Plug the built-in wiring harness from the ballast into the socket on the HID headlight.