While they don't say what the changes were that allow the increased capacity, I would suspect it would be similar to what Mec-Gar does with their nesting springs and follower
Personally, I like the Mec-Gar flush-fit 18 round mags ... which, of course, fit it all the 92 versions mentioned in the OP. Gotta love the Mec-Gar "Optimum" (plus-2) mag that holds 20, too ...