I don't know how to answer your question, but;
The basic idea is to make the MAS and the throttle body the only restrictions to filtered air intake.
The benefit of the drilled air box for me was getting the intake, before the filter, higher off the ground (the stock location is behind the bumper, pretty easy to suck water). A side benefit (for some anyway) is the sound at WOT, nice growl!
Exactly where do you mean by "cutting part of the opening that sticks into the airbox.?