My friend did this mod to his turbo charged 606. He did the "fresh air mod" that works on NA 606's. Pretty much put a little air filter on the EGR intake pipe. We got 1/4 of a mile down the street and the CE light came on and cut boost.
However I do not think boost was bleading off through the filter. When we first tested it in the garage their was suction. Makes sense exhuast gas needs to get pulled through that tube.
I suspect their is a temp sensor somewhere. Further study of the 606 FSM is needed. Their is probably a way to trick this sensor.