Apparently I did - had not followed your link. It isn't really a study. I did have a link to an actual analysis and evaluation of the construction and filter capability of these filters on some MOPAR web site, but it does not seem to be working.

 

The std Frams use cardboard endcaps from what I remember. Not really acceptable (to me anyway). The TG versions are built acceptable but I don't really like the idea having to spend more just to get a decent build quality on a filter.

I go Napa gold as their oem maker is Wix.