i went for a ride today and unlike most of the hooligans on here, i usually keep the rpm under 6k rpm. today, my inner hooligan possessed my right hand and twisted the throttle a little more. on the freeway, 3rd gear, passing 6500k and the bike's exhaust note changed from a loud throaty roar to more of a wail. is this natural? i have dual titanium arrows and a tors tune on the bike... thanks for your thoughts.