SR20 Overboosting - what besides vacuum leak?

[lourens13]

SR20DET, TD06 external wastegate, etc.

Last weekend my car was overboosting to almost twice what it had been tuned to / set at on the Greddy Profec B. Tried turning the boost down on the Greddy, but didnt make a difference in the slightest. Besides a vacuum leak, what else could cause this?

[usmcgetsome]

ensure your your greddy boost solenoid is operating properly and of course check your remove and clean up your waste gate! last but not least it could be boost creep from the manifold.

[EsChassisLove]

What is your wastegate spring at?