I have the same noise.
Checked both turbo hoses twice, they are fine.
Engine appears to be louder than usual too, but put that down to blanket off EGR.
Symptoms: Pulls almost Ok in 5th when putting the foot down once.
Lift off the accelerator for a second, then foot down again no more boost.
Engine check light comes on sometimes and car enters limp home mode.
Light increase of black smoke.
If I disconnect the vacuum pipe to the Turbo, car runs perfect above 2500 RPM.
No black smoke at all and the noise are gone!
No engine check lights and pulls like a train.
I live with that since 4 months now.
Replaced MAF, VNT Solenoid, Vacuum pipes and cleaned the MAP twice.
I wonder if the MAP gives the wrong boost pressure readings.
Reporting more boost than there actually is under acceleration.
The ECU injecting fuel that does not get burned producing black smoke.
At higher RPM (2500 +) the fuel / air ratio is within “normal” range and the black smoke clears up?
Drives me nuts..