I have an 02 WRX with TBE, Up pipe, Samco Hoses, Silencer removal with Perrin filter. Today I was driving around and wanted to see what psi I would hit in 4th gear. The boost gauge started to climb to 14-15 psi then dropped to 10-11 psi and kept pulsating between them throughout the rpm band. 5th gear was doing the same thing. 3rd gear was only hitting around 12 psi. Any ideas what could be causing this problem.