It's been about 6 wks of happily driving a CO BRZ here in CA

You can add me to the CO>CA Cartel.
Find a good dealer who will help you thru the process. My dealer sucked and was not knowledgeable when I asked about requesting the paperwork, etc. You'll need the "Certificate of Origin". It's a very important document and it was like pulling teeth to get this from the original dealer. This is a certificate that follows the car from the Port of Origin and comes from Subaru.
I also paid the CA tax at the Subie dealer (Arapahoe Go Subaru, near Denver). They miscalculated the tax which is an easy mistake to make so I don't mind.. but i'm still going thru the refund credit process because I ended up paying about $170 too much. Have no idea if i'll ever see this refund. Sales people there are great. Their Finance and Admin staff... Whole different story!
Btw.. not sure if this was mentioned. Evidently they require a smog every 2yrs instead of the first 5 year waiver.
Regardless.. couldn't be happier w/ the car. Thank god I didn't settle for a FR-S
This was during the drive home passing thru Moab in the wee morning hours with my bro.