HID possibilities

HID headlamps require special starting gear to operate. Metal halide lamps used in other applications, like warehouses and street lights, have long warm-up times before the lamp produces its full light output. This characteristic is not a severe limitation for these applications, but imagine having to wait several minutes for the headlights to turn on! To avoid this unacceptable situation, the ballast provided with HID headlamps also provides a very high current to the lamps when they are initially started so that they will produce enough light when first turned on. Additionally, HID headlamps are doped with xenon, a material that allows these lamps to generate sufficient light output within a short period of time.
HID headlamp illumination may appear bluish in tint, and the color of these lamps may appear to shift slightly as a car equipped with them passes by. This is primarily caused by chromatic aberrations at the edges of the projector lenses used in these systems, and partially because the discharge arc might not always be perfectly uniform in color, with light from different parts of the arc being distributed to different parts of the headlamp beam, researchers have found that "bluer" light sources result in improved peripheral visibility.

HID headlamps are currently found primarily on higher-end vehicles, One factor that may impact their use as an addition is the fact they require something of a higher voltage to operate around 50V I believe and in this country they cannot be used unless they have an additional self leveling mechanism.. I have seen conversion kits for other cars such as Subaru imprezas and these were in the region of £1500 just for the kit with possibly a high labour charge to fit as they require specialist attention to fit Not a general DIY job.
I managed to by some good quality blue tint halogens from http://www.autobulbsdirect.co.uk/
They look good and seem to be brighter, when you are in the countryside away from street lamps you notice them the most.