the result is a big hole in your wallet for a part that makes the car unsafe to drive at night, produces very poor light output for what it is, is a huge attraction to the police, and makes it very difficult for other drivers to drive. They're also huge pieces of crap for a quality stand point, and will break in a very short amount of time.
The only way to safely add hids to the car is with a retrofit. Remember, hid bulbs are for headlights designed for hids. The stock 968 headlights are designed for halogens. Even if you can get an hid bulb in there(which you can), the headlight is still not designed for that bulb.
I've posted a lot of posts as to how to go about adding hids in a safe, oem like manner.
