[EC900]

I believe it will also restrict any major oil build up and blowback. Works like a check valve, they need to be cleaned out periodically. Mine has a little screen or perforated end cap on it, doesn’t look like the one on the PP site.
Do you find your air box somewhat oily? A film is reasonable, but in worse cases there’s a drain hole and a hose that routes any oil out should it accumulate.