Optics and light sources evolve constantly. When the discharge technology came out in 1984 it was 14 seconds strike time, 5200K and lamp life 800 hours. Today its 11/1000ths sec , 4200K and 5000 hours. I see no reason why this would stop and the optics have evolved in the same way although perhaps not as fast.
10 years ago your lens was glass and the reflector steel. Today its 100% plastic
Pre 2003 model HID's on Golf & Bora used a seperate ballast & wire harness that ran to the back of each lamp.
The 2003 model HID's have a ballast that is attached directly to the back/bottem, thereby eliminating the other mention items above.
There are of course a few more differences but those are the main points.
A forum community dedicated to all Volkswagen owners and enthusiasts. Come join the discussion about performance, builds, modifications, classifieds, troubleshooting, maintenance, new releases, and more!