When Steve & I first started talking about this build which by the way started on the drawing board as a GMR 113 we talked about air cleaners and during our conversation about what breathes better than the stock Ventilator air cleaner, Steve gave me his opinion on the H.D. Ventilator and opening the backing plate, The H.D. Extreme Billet, & a billet one very similar to the H.D. Extream made by Kuryakyn. He went on to state the the open ended types allow noise through the opening. When he recieved my bike we made a decision to try the new T Man Zero Loss Air Cleaner that he advertised on his Facebook page however when I contacted T.R. he stated he was having vendor problems producing the kit so I decided to add the H.D. Billet Extreme to the build. It is more prominent when I bring my ear next to the air cleaner.
Maybe Steve can explain this better than I
BostonBoy