Its deff the heat shield I went to Performance and they fixed the problem

 

im on 350z s techs, drive carefully, but bottomed out very hard on monday. i noticed this EXACT sound later that night. the next morning i slightly bent the drivers side tail pipe and the sound stopped for a few hours. this is the 4th day of this vibration noise. i really hope it isnt the muffler but as soon as i get new front tires on the car ima go full true dual. any suggestions appreciated.

 

this sounds just like the noise my muffler is making and mine is all stock. sounds like a loud vibration thump cracking in and out while i rev the engine.sounds like air is being held from escaoing from the muffler

 

the baffle thing the dealer said is very likely. i had the same problem it would rattle here and there at certain rpms and i ended up tracing it the the drivers tailpipe inside. it turns out the moisture that collects in the exhaust while the cars off sits in the bottom and rusts the tac welds on the baffles in the muffler eventually leading to them cracking and rattling back and forth.

 

Yup 100% agree same thing that just happened to mine due to having a bag gasket where the muffler meets the mid pipe i believe it is but when i start my car n hear it buzzing and making the noise were talking about i tap on ym muffler while its running and can something moving around inside there. And the gasket that was bad has let run and condition into the muffler causing it to become wet and casing rust and corrosion inside the muffler loosing up whatever in there. It just happened to my car this winter and i live in AZ but when it would get cold out over night like freezing or close too and id start my car in the AM you could hear it and also see water dripping from the exhaust pipes and where the gasket to the mid pipe are would also leak some water from the cold weather condensation. So i need a new muffler for sure. My noise is more of a humming/vibration noise it would do on n off during start up but completely go away after driving, I have another nose that accures during 1500-2000 rpm acceleration aldo and that's a rattle and could be related to the muffler but was told it was my resonator so not sure yet havent fixed either but will so n let you know