I have looked everyware on the internet but dont find the correct size før the restrictor you should use on a sti ppp -02.
Whas told by TSL it should be 1.0mm.
It was 0.9mm from start and I changed it to 1.0mm.
But I still get turbo flutter on 5 and 6 gear in low revs(2000-3500rpm).
And the boost is pending between 18-21psi before it becomes stable.

 

try getting in touch with prodrive, they should know the answer.