[easy]

At about 5700 rpm my bike gets really loud, and deep sounding (sound good, to me), and then at about 6k rpm the sound sort of smoothes out. anybody know what that's about?

 

[Eman]

my 2K R6 at about 4500 to 5 grand freakin' wakes up (almost hits like a turbo)

 

[02R1guy]

all motors do it at various rpms and tones. My Yzf600 used to do it at 4500 I think