Intake scoop or snorkel. The piece connected to the airbox to force cold air in. It has two push clips. See if they are missing.

 

that might be it but i really think its his dv/wastegate switch out with a 9 WG cause the 8's WG are crap/plastic!! the down pipe has nothing to do with it but it is needed with those boost levels i dont understand why you dont have one???

 

ok i just seen you have a 9 so forget what i said about gettin a 9 WG. this might sound dumb but check to see if you WG is on backwards cause mine was right from the dealer still i dont think that would cause the problem but its good to check just in case! check to see if you have a vacuum leak also

 

aftermarket gauge or stock?

 

It's the plastic "tube" that runs from the top of your radiator support to the intake box. There should be two plastic clips holding it down. Make sure it is secured then go from there.

 

not everyone keeps the stock intake snorkle on when they switch to an aftermarket intake. It normally feels like hard boost cut when the snorkel blocks airflow from to the maf. Or it could be another variation of the "snorkel syndrome"