The real irony, however, is that Mann and German Bosch are used as OEM equipment, and in European applications are fantastic filters. For North American options, unfortunately, they are the Purolator Classic and Bosch Premium, respectively. At one time, I had complete confidence in those filters.
As for air filters, though, I haven't seen a lot of issues with any good name brand or OEM filters. The Canadian Tire jobber line up here used to have some pretty meager pleating on the round filters of the day, and Fram had its bad moments, too. Back then, I stuck mostly with OEM filters for the Fords. In the past twenty years or so, OEM, Fram, and Wix all suit me fine for air filters. For the Audi, it was Mann.