cool idea, and write up.
- Another reason to do it, is allergies. You filter out the pollen - good for not sneezing while driving
- you would increase the capabilities of the filter extremely if you would leave it folded up like it came from the package. That is having this zickzack pattern is a real good thing. It increased the area tremendously, for examples look at air filter, fuel filters, oil filters and so on.
- but this would mean that you have to sandwich the filter material somehow under the shroud, thus raising the shroud.
- How much space is left between shroud and cowl tray (or what ever its called)
- you could fab up a piece of metal / fiberglass or what ever and build little shield over the opening, leaving the underside / side down / front open, so air can enter. This would probably keep water out, as long as the air isn't being sucked in. the drawback is, that probably the noise of the blower is increased as you can probably hear the air being sucked it, by the "funnel" you build by fabbing up a water shield.
As you have the mounting pattern, wouldn't it be possible to go look for a already complete cabin filter from another car that would be made to fit?
This approach would be easier for me that only has the opportunity to shop online and most of the time has to select a special car to order parts for (e.g. RockAuto)