mad question, this external wastegate, it is vented to atmos, and not rerouted into the exhaust right?

i would suggest looking at the vac hoses on the wastegate and checking they are plumbed in correctly.

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also worth pumping in some air to one of the EW ports to hear it open and close

(engine off obviously).

here my tial just for reference
https://www.youtube.com/watch?v=mUQYhcWMkqc