loosing boost pressure after 10 psi

[The j man]

hi i rebuilt my yd25 i didnt have the car before the rebuid so i don't know how it drove
i get upto 5 to 10 psi and it cuts out straight away,
i bought a new solinoid put that on it didnt help, i changed all the lines still nothing
i switched the solinoid lines the vac and the one that connects to the turbo and im getting over 20 psi and it will go more but i keep it in the factory psi what could it be ? does the scv cause this issue?
also there is a very loud noise from the turbo that goes away a few minutes after driving
also can i run the car with the lines switched for now untill the problem is fixed keeping it under 20 psi ?

 

[The j man]

?

 

[Kzin]

Just make sure your Vac hoses are connected correctly. like the picture...

and make sure the ones on the other side of the engine are also on correctly.

If that is all correct and the problem is still happening, with the engine running check for vacuum at the turbo end of the pipe connected to the actuator, ensure that the Actuator moves up and down when you pull the pipe on and off, Down when it's off.

If there is no vacuum there, check the pipe at the Vacuum Solenoid that is closest to the air box, refer the red Arrow in the top image above.
Vacuum there but not at the turbo would indicate the solenoid has a problem (could be Electrical).

Check for split hoses right through the system, whilst you are checking the connections etc.