Cashburn,
Yes, and you can paint a shield on the bulb, and you can buy an adapter with a shield. I have tried these things and they are no substitute for a correctly engineered projector assembly. If you would like to buy any of these half-a$$ed solutions, I will be happy to let you have mine very cheaply!
It comes down to handling the stray light. I used to get flashed by oncoming cars all the time. One of the strangest things happened while driving at night in the rain. You, of course, have to maintain 60 mph or better to keep the rain off your head while driving topless. Looking up above the car, the headlights produced a flat plane of light that was exactly vertical. Through the wall of light, you could see the raindrops coming right at your face, but they disappeared and never hit you. It was very cool and it clearly demonstrated how much light was being wasted.
