I've had nothing but good experience with PSI.
My first order was shortly after purchasing my first lathe (which I have since sold). One of the items I ordered was a stopper mandrel, and I placed the order on the basis of information that was printed in the instruction book. About an hour after placing the order, I discovered that the instruction book contained bad information, and I had ordered the wrong mandrel. I sent a followup e-mail to customer service, and when I received the material a few days later, they had recognized the correction.
Typical turnaround time for order is less than a week. Usually, if I order in the morning, the order ships that afternoon.
And PSI Technical Support is really outstanding. My new lathe is a Turncrafter, and their tech quys are a great resource of information.