I think its easy to see how engine builders feel.
ALL production cars, motorcycles, dirt bikes, lawn mowers, generators have been shipping with air filters for over 50 years and its not because the manufactures want to spend extra money.
I also think most model A engine builders insist you run an air filter or it voids the warranty.
Unfortunatrly this discussion gets repeated almost as often as oil arguments

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All prod. cars in the last 50 years have larger eng's. and draw in a heck of a lot more air then a 40 hp. 80 year old "A" does.
Dirt bikes and lawn mowers need an air filter for obv. reasons, and so does an "A" if it is driven on dirt/dusty roads most of the time.
On todays roads, if your "A" has eng. pans and the correct fan, most of the dirt/dust will be blow'n away from the carb. intake.
If your going to get an air maze, you might as well get an oil filter also, and why not a GPS ?
It's JMHO, but i don't think the air maze is worth even one fire

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