S1 rs turbo running FRST engine with a T3.

car is peaking at 10psi then the needle drops right down and only holding 5psi. thought it was the actuator but i have a forge item and took it apart and its fine, has a blue spring fitted.

I have discovered some cracks in the rear housing of the turbo would these cause this kind of behavior?

I welded them up today but it doesnt appear to have made any difference?