just take it off
you need it to pass emissions/not have a CEL and you would have to block it off to prevent a major exhaust leak at the turbo manifold and a major vacuum leak at the intake manifold.
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because when the intake manifold sees boost, the egr will open for lack of a opposite pressure... thus resulting in a boost leak
how much are u boosting? the turbo may just be compensating for the leak by pumping more air = spinning faster than it should
i'm not going to try to convince you because i don't have any solid proof except for my own experience. and it would be really hard to describe it without showing you an EGR and pointing at sections with my finger...
if u ever get a chance and u dino the car, try putting your hand around the breather and see if u feel air coming outta it.
yeah I have dynoed with it capped and I have dynoed with the breather on and I can't say if I felt a difference looking at the boost, but I wasn't feelign for air either. I wonder if I could feel it just revving in neutral without a load on it, it'll go into boost just not fully.