I used to have HIDs (8000k) on my Ford Festiva...they were the best thing that car every saw. As for Mustangs, I've seen a V6 with one...didn't look too good, they were too blue. If you do go with HIDs, be sure to get a projected housing so that you don't blind other drivers (note the pictures above). I sold my HID kit used for $150, so someone got a REALLY good deal because it had only been used a few times. Installation is nearly as easy as installing replacement bulbs; you just have a few extra wires. I wanted to shoot myself in the foot for paying $60 to have someone install my HIDs. Like someone else said above, 4100k is probably the best to go, but I loved mine @ 8000k.
As for the prices...they have gone down since they started selling a few years ago. You can find them anywhere from $150 to $800.
Like I mentioned above, there is no "retrofitting" involved. If you get the right kit (for a Mustang, it's 9007), they should go right into the stock housing.
If anyone can afford to buy me some...please let me know!
