K & N air Filter...worth the price?

For $35 on amazon the AEM dry filter not only flows better than OEM, protects really good too. When I inspected the inside of the stock air box (top side) post filter, I was expected tons of dust after 40k miles using the AEM. It was actually clean to my surprise.

I think it filters down to 1 micron. A human red blood cell for reference is 5 microns.
So AEM filter is same thickness as French President = 1 macron?
 
I recently put a drop in K&N filter in my 2018 Mazda 6 sport and haven't noticed any difference. But what I did notice while doing so was Mazda put what looks like a secondary fine mesh filter on the top of the airbox that can't be removed any ideas on why they did that and if it's restricting air flow?
 
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