Strange noise after Carven install

[Profanesix]

I went ahead and removed the resonator after the muffler and it wasn’t enough of a V8 tone that I was after.  Installed a Carven TR muffler,. Sounds amazing. They left the flapper installed though since I had ordered a Range AFM to disable V4.

 

the issue I am having only happens when driving. If I get on the gas there is this strange high pitch noise. If I toss the truck in neutral and do it it’s pure engine and exhaust. Drop it back into drive and can hear that high pitch sound again. Only happens with hard acceleration. Never heard this noise before. Will try to get a video clip with the go pro soon. 

[Profanesix]

Just found out that if I really give her some with it in neutral I can hear the sound. And it sounds like a loud fine high pitch rattle. So now I am thinking it’s the flapper.. damn it think I found the issue. Can this post be deleted? haha