My Corvette is a 2006 convertible with paddle shift. During heavy WOT acceleration I hear and feel an oscillating harmonic vibration that happens between 3000 and 4500 rpm. The service manager at the dealership was able to duplicate and sustain the vibration by holding the speed around 4000 rpm while going uphill. He says they all do it and it just goes with the territory. My 2005 Z51 coupe with manual shift did not do it. There is no degradation in performance as near as I can tell ... runs like a bat out of hell ... but I do worry. Anybody else out there experience this?