I just purchased my second Porsche from a Washington dealer and registered the car in CA. I will reiterate what others have said: get your CA sales taxes refunded to you, obtain the MSO, get a smog check and then go the DMV. A pain in the ass, I know, but you will save yourself a lot of angst if you do the whole process yourself. This should be 4 hours of your time, all in.

Dick