Ask yourself the question, where for is a airfilter.. to block air? No.. just to keep dust (and all other debre) out of the engines cylinders.. If you drive the car on a "clean"day without a sandstorm.. it will be no problem.. When engineers fidle on engines half of the time the filter is not in place.. Just remember that it's there for protection of the cylinderwalls and stuff. If the air around the car was always clean you wouldn't need a airfilter.
Hey Gundee, i get that you want a faster car (By removing the airfilter) but in a autocross (With lots of dust!) I especially would use the filter as the cars in front of you make a lot of dust... or.. do you always drive at the front? 👍