This article is from the VW Technical FAQ, by with numerous contributions by Jan Vandenbrande others.
A: They are pure CRAP!!! They are too restrictive according to Roc Goolen. [If
you really want to filter your air, go to a hardware store, buy a furnace
filter for a couple $$ and rig it up somehow. Jan...later I tried that,
and wouldn't you know, that too restricted the airflow!
At least I only spent .40 US$ finding this out.]
Note that the filters that APS used to sell were made by Climismann (sp?);
they are now selling units made by Bosch and make the claim that they "work
much better." [Hmmmmm.... Ed.]
 
Continue to: