So, I've seen a couple of harnesses for about 100 bucks each on ebay. Is this a DIY at all??....It doesn't sound to me that it's any more than remove the bumpers, plug and play, find the right spot to, look for the right connections, etc. I've done similar jobs on my past BMWs. The retrofit is about $4000 at the shop. A pretty penny for JUST the parking assistance. So, what do you guys think, or suggest??