On my way home from a long street ride yesterday I did a good stretch of Highway , at least 40 miles of it before getting back on secondary roads . I was playing around with the throttle watching Rpms and the speeds and listening to the motor . I may have touched 9000 rpm a couple times . Once I returned to backroads my bike seemed Throatier . More air box noise , a Deeper , Throatier sound than I remember . I figured it was all in my head . But after I got home , got into family mode for a few hours and let the bike cool fully . I took it out later in the night to run an errand : ) The bike was definately quieter again . And I ran it up and down a favorite country backroad to "Test " it . Definately quieter. Just air box noise , not motor noises . ???????