Sounds like there is still a restriction in the intake or exhaust, take the exhaust off as close to the turbo as you can and fire it up again
According to his first post, the exhaust doesn't enter in to it.
Supaconducta, if you pull the snail off, that's the aluminum piece with one bolt holding it to the intake manifold, there will be a screen under it and I'd be willing to bet it's got a major pile of foam trapped on top of the screen blocking off intake air. The original filters that came on these turbo models had a paper filter with a foam layer lightly glued to one side of it. Sounds like someone installed one upside down, the foam side goes DOWN facing the dirty side of the airbox.