I guess it all worked out.. And the reason it drops so low is the bleed rate is too fast with those restrictors missing.. Their calibrated to allow a specific amount of airflow through and minimize spiking so its no surprise at all.. You can buy a new hose assembly with the restrictors in it from Mitsubishi..

 

question: would it hurt to drive the car around while I wait for the part to arrive?

 

Nah, too low boost means it'll run a little rich, and you'll be down on power, but it won't harm anything.

 

I am having somewhat of a similar problem...my dealership just replaced the wastegate syllanoid because they thought it would fix some other issue....as soon as i got the car back i can only push 17psi max...the down to like 15 or so....could they have forgot to put something back in...or change a hose incorrectly to yield the resulted decrease in boost pressue? I am planning on getting an MBC until i can get the xede but want to make sure there isn;t somethign else wrong before i set a constant pressure of 19 psi.