Engine Ping on 91 Octane

Rocketman

Its a real thin metallic sound. The best way I could describe it is the sound that is made when you bog an engine just before stall. Is there a chance that this might be something other than pinging? So far nothing can be found that could be rattling underneath the car. My only thought would then be something internal. I know the transmission in these cars is generally pretty noisy but the sound usually doesn't appear until after the clutch is fully engaged.