You might have had OK result and I did not but the general issue is Holley's assume the bowl will be at atmospheric.
Not saying it can't be worked around, I'm sure it can. And I'm sure there are instances where the Xtreme top is an advantage.
Connecting the vents with tube that has side and bottom holes is done a lot anyway, and would help prevent the velocity impacting the bowls.
With a short filter hieght and drop base, its probably the worst case. That's what I was trying to address and eventualy went to a well shaped spun aluminum lid.
Good discussion over at speedtalk.
Engine Masters' Air Filter Test - Don Terrill’s Speed-Talk
