Seeking expert help on 2005 Mustang GT issue

There is a nasty sound with my 2005 Mustang GT. When I am shifting from 2nd to third, or third to fourth, immediately after releasing the clutch, or when the transmission is in gear, and you do a rapid acceleration (as you would when you have to overtake someone), a noise resonates. A noise that sounds like a quick succession of rapid metal taps (very similar to valve tapping), or maybe some sort of gear grinding. The noise only lasts for about one second. It is intermittent, not overly loud, but you can definitely hear it. I am really trying to get some suggestions as to what it might be. I had a friend ride with me, and he thought it was a synchro problem. All advise is welcome.

Thanks.
Abzuli99

take it to the ford dealership if its under warrenty

It could be various different things. A heat shield on one of the cats? It's gotta still be under warranty so bring it back to Ford.