I got a boost leak tester from STM.

Popped it over the turbo, looked up the compressor line and as I'm filling up the system with pressure, something is kicking on and reducing the pressure. It sounds like something under the dash/back of the motor.

Anyone know what it is?

 

nevermind, it was the hobbs switch of my dual pumper going off at 15 psi, disconnected the fuel pump and everything worked as planned.