Sounds like it to me, 12 psi on stock ecu is too high in my opinion, that said it's about 20 yrs ago since I had my RSTs

Before I had mine chipped with a Bayjoo chip I had an incar bleed valve which was a balancing act between having loads of boost then the sudden boost cut, which was interesting while overtaking...lol

Before having the bleed valve, Mine used to spike about 15 psi but then drop down below 10 psi so not to hit boost cut.