The first time I looked at the air filter on this bike, I got my introduction to the dreaded rocker breathers and a massive oil slick inside my air cleaner. After much debate and (by now) education from reviewing everything Harley - I decided to kill two birds with one stone with this Arlen Ness Big Sucker Stage 1. After some carburetor tuning I am pretty happy with it. Only thought was I wish it had the billet cover instead of the stamped steel - you can see how it dimples in the center (even when barely snugged)