Below is a link to a thread from a Porsche 911 forum....It may be of value. I've also pasted some excerps below.....
"Since i didn't see anyone recommend single stage urethanes, I will. I've done 5 cars with DuPont base/clear and the last 6 (along with my current 911) with single-stage PPG urethane (DCC concept) and a couple of beaters with PPG Omni (an inexpensive option - for an airport car). I really like PPG it's my personal preferrence. Do not use Imron (trade name) good paint but VERY dangerous to spray. I used to paint airplanes and I loved reading the warning about permanent central nervous system damage.
I use the single stage because I find clear to be more difficult to spray well than color and it's easier to touch up. If I were doing a car that saw limited use, I would use a base/clear."
"I paint my own cars in my garage. I have done maybe 20 cars over the years. I would recommend finding a local paint supplier that sells quality paints and is willing to help a DIYer. I use Dupont stuff. I have called the 1-800 # for Dupont in NJ. The guy at Dupont is willing to talk your ear off about painting stuff."