As more evidence vs pure speculation/hearsay, found a link* to a bitog post for a made in Korea Pronto filter with pics. It is not difficult at all to the similarities of construction to the XL. The coil retainer spring, internal dome coil bypass spring, numbs on the thread end endcap and same baseplate design.
Just add a red colored sealing gasket and silicone adbv, black paint (perhaps media upgrade) and you'll have an XL. The dissection details of the XL can be seen
HERE.
It should be noted for reference that Puro filters do NOT use a coil retainer spring, uncovered internal dome bypass, nubs on the thread endcap or a cello baseplate cover.
As specifically noted in the OP though, the ISO efficiency rating of 99%>20um is quite good, if not the regular price.
To me, much like the DriveWorks filter made for AAP and sourced to an unknown manufacturer in China, the XL is a higher end made for AutoZone filter by an unknown manufacturer in S. Korea.
As an aside, imo Fram filtration should be thanking the observant and detail oriented posters in this thread that first pointed out and brought attention to factual information posted including the hotline number AutoZone printed on the box and confirmation. Also for noting baseplate design, coo and other differences and didn't accept off hand the implied relationship ChampLabs/fram filtration as first posted in the OP.
I'll post one pic from thread, others with detail are in the link.
*
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1838720