The issue I'm describing is a result of the fact that your 16g can only flow so-much-air. On a 2.0L engine, it should be able to hold 23psi or so to redline. But, if you put it on, say, a 2.3L engine which consumes more air to begin with, it may only be able to support 18psi to redline. So, suppose you have a big boost leak or your bov isn't sealing correctly. Then not only is the engine consuming air... but also you're wasting air out the leak. That means that the turbo has to move MORE air then it normally would for a nice tight 2.0L. This is going to reduce the boost level that it can support.
As an exaggerated example. Suppose that you pulled the bov off and didn't seal the flange. You'd have a MASSIVE leak where the bov used to be. Now there's no back pressure from the engine and all the air is fee to just flow right out to atmosphere. The turbo would NEVER build ANY boost. It would overspin and push a sh*t TON of air against zero restriction and you'd get 0 psi, all the way to redline.
Find the leak...