hmm i too have the same problem, i also find that if i go at hiway speeds and keep it at a steady low r at light throttle it makes the same noise, it does it when i start up and it is cold, then i wanna say anything over 2500 rpms it goes away, and it wont do it as much warmed up but i can finesse it to do it, please figure it out, cause it pisses me off, doesnt kill my hp but kills my head