[Kracka]

The little vent is there to bleed off boost pressure when you close the throttle so the wastegate can shut, the barb needs that little hole in it for proper operation. Sounds to me like you might have a serious case of boost creep. Is the wastegate passage ported? Does it have the larger 34mm flapper or the standard (29ish)? What o2 housing is on the car? Did you use all brand new vacuum lines on the boost controller?