DNA Air Filters - Stage 3 Air Filter for BMW R nineT - Billet TopNew DNA High Performance Stage 3 Kit specifically designed for the BMW R nine T. Internal diameter design matches the R nine T throttle body. Venturi intake design smoothens and improves the air flow. No need to remove the air box! Only the connecting tubes, from the air box to the throttle bodies. Filters designed not to interfere with the riders boots! Racing, custom and road use. This Stage 3 application is developed for race & track use and in