Finally driven enough I can make a fairly Intelligent (?) judgement. My car is a 2012. 4,500 miles. California (not too hot). Two changes of Redline gear oil. Last winter I installed a NACA duct. 12 inches forward from the bevel box. My conclusion is that the BB noise is still there, but at 1/4 the sound level when during a long hot drive as opposed to a scream between 40-60 MPH before the duct installation. Now the BIG question is---has my BB worn in properly OR have the changes ie, oil changes, NACA duct made the difference?
