loosing boost.... wastegate issue?

[95TSiNewbie]

Last night i was driving around and a GT Mustange decided to act all bad ass and rip of the line, so i followed and out of the cornor of my eye I noticed my boost gauge warning light flash on (25psi) and then shut off. When i looked over my boost was falling all the way down to 0psi. Its weird because if I keep the car from opening the wastegate (tial 38mm) it will hold 20 psi. But once the wastegate opens boost falls off completely. Anyone have any similar issues and know a fix or atleast a little insight? Oh and Im using a dejontool MBC if that makes any difference.
Thanks,
Bryan Tracy

 

[laserspeeddemon]

Have you done a boost leak test?

 

[95TSiNewbie]

I havnt checked for leaks since I installed the new turbo and FMIC but everything was fine till 2 nights ago. Ill try and do another check tonite. I guess I just dont understand why if I set the MBC at 25psi it will hold 20psi if i keep the wastegate from opening. But if I turn down the MBC to 20psi it will no longer hold it when the wastegate opens.