Manual boost controller, or stock?
The only thing that - bar a fubar'd turbo - is going to inhibit that turbo is the wastegate, and/or an exhaust leak. If you run a line directly from the wastegate actuator to the compressor, you should hit boost fine. I performed this test a while ago, and used it to identify a faulty OEM EBCS. Do NOT floor the car, but it will let you know if it is solely the boost controller that is inhibiting boost, or a pre-turbo exhaust leak.