UNI filter worked well with our cowl hood on our W5 mill.... unfortunately this set up came in at .75" too high, so the 4150 carb is on for the time being. I never ran a filter on the Mirada. Dang top of the carb was up in the Dart Sport hood scoop I was running.... no room.

....and yes, these are basically "bug and rock" catchers imho, kind of like the K&N filters I see in so many diesel trucks.... with blowby.