I just got my car yesterday. When I did a boost test today it ran a 10-8-7 boost pattern in 3rd gear. I have run a search but come up with nothing (search engine sucks). If anyone knows some common causes of this, please post.

 

Check for boost leak in the intake path. start from the y-pipe, examine the rubber couplings very carefully. Boost leak is the most common cause of pressure drops. Good luck

 

I would go one step further. Remove the y pipe and the rubber piece that attaches it. It is hard to see some of the leaks that are created there but if you remove the rubber sometimes the little cracks become evident. This did happen to me once, similar boost pattern. The problem was a small split in the rubber piece.

Chris