Wix XP Failed due to the leaky bypass valve, in theory there would be non filtered fluid getting through that valve going straight to your engine. The flow would be radially inward in for the engine, but in our test the air pressure in our test should have been pushing it shut as it was radially outward.
The AC-Delco is a big question mark if it would affect the efficiency, I didn't like that seam being the only spot for the bubble point. It is possible that it would sill work fine. The manufacturer could give us the pass or fail pressure. Otherwise we would have to get into many more tests to determine that Pass/Fail pressure for them. That is R and D they would have to pay us for.
I wish it would be possible to have a filter housing made to test those specific elements.
We have to keep in mind that this was only one test on one filter so statistically it is insignificant and no conclusion as to which is best can be drawn. But we can certainly learn a lot from this data.