Sweeny is correct. Last year at VIR, I picked up a student who was driving a fairly stock 930. His instructor was not allowing him to shift at all. The instructor was scared of the boost, and only allowed him to get it into 3rd gear and then he had to drive the entire course in 3rd. A 3.3 Mile track in 3rd gear in a 930 SUCKS by the way!
While I'm not a pro by any means, I have driven a 930 on the track for 5+ years at this point, so I hopped in there and the guy had a blast with me as an instructor because I knew what to expect, knew how to address it, and basically allowed the guy to really enjoy his car.
So Sweeny is correct, find an instructor who has a fair amount of seat time in a 930, and that will help!