Lets think about this some more.

Since we don't know to what specifications Napa has their filters made, nor do we know when they may change vendors or filter constuction to help their bottom line, (after all they are in business to make a profit) & napa doesn't make engines nor test them for hours on end, to decide how their filter should be made.

But Ford does & has to warranty their product, & specifies a filters construction, inside & out, after all of those hours of testing & engine tear down & inspection.

So it seems to me Ford would likely know how to specify the construction of a filter for their engines, or when any changes may be needed to a filters construction later!!!!

Thus it seems to me the benchmark to meet, is still the manufacturers product!!!!