Fit a boost gauge,and if you can't find another plastic grommet, you can always modify
the other restrictor near the wastegate.
It's on 1 of the 3 hoses connected in a T.
You have to make the diameter of the metal restrictor slightly bigger to reduce pressure.
A very small difference in diameter makes a big difference in boost, so fit a boost gauge to
set the pressure correctly without getting fuel cuts.
You can usally get 1.2bars without fuel cuts.