Southern CA P337 shop
 

Any suggestions on a shop in Southern CA that can do a good pre-buy/annual inspection on a P337?

The folks at Super Skyrocket are in Southern CA, and are experts at pressurized Skymasters. The phone number on their web site is 1 (760) 929-2800. Their website is http://www.superskyrocket.com

A place that may be a little closer to you is Tule River, located in Porterville, CA. They are a mod shop for Skymasters, and one of the approved places to make a Super Skymaster. Their phone number is 1-(559)-791-1866. Their website is http://www.tuleriveraero.com/