I got the Amsoil drop-in nanofiber air filter, it is re-usable. I just blow it out with my air compressor when I am doing maintenance work. I live on a dirt road, lots and lots of dust all the time, so I am constantly blowing it out. My filter minder has never moved so I do not know how reliable it is, but my filter HAS been dusty and needed cleaning. The first thing you would notice is a decrease in fuel mileage, higher egt's, smoke and lessening of power.
CD