Ok, so I had my turbo reman'd and ever since I reinstalled it my car hits 4psi, then at 5,000 the wastegate goes wide open and the car has spiked to 15psi by 7,000. All the couplers are nice and tight, theres no cracks in them either. I really don't think this is a boost leak and the wastegate is ported to 40mm. Vaccuum lines were redone and are snug as well. I've just been assuming it's a messed up actuator. For reference, the turbo is one of those Knightsports T3/4 jobs with the larger wheel and compressor housing, but retaining the factory hotside. Thoughts?

 

wastegate stuck open? So it has low boost in low rom and then when you hit 5k to redline it is at 15psi?

 

check the wastegate diaphragm with a vacuum pump.