I've had PDC retrofitted on both the BMWs I've had, the X5 and the 330xi. I just took it to the dealer to do it. When I attempt DIYs, things tend to go horribly wrong. The X5's installation ended up being about $1300 including labor. I was without the car for three weeks, because they kept ordering the wrong parts. It was worth it though. Once you have PDC, you'll wonder how you lived without it. I would recommend the full front and rear PDC kit, instead of the more obtrusive kit with only two sensors. The full kit gives you better coverage, and it also helps on the front, which can come in handy while maneuvering in tight spots. Also, the full kit gives you a button so you can turn it off. Or on. I sometimes turned it on in traffic to see how close the car behind me actually stopped. Good luck!

__________________