A strange sound has been occuring in my car recently. When i'm accelerating from 0 to 40 I hear a really strange sound going on throughout the cabin. It sounds like my exhaust isn't hooked up properly and is just hitting the undercarriage side to side.

I think something is wrong with the catback because I hear the sound directly underneath me. What do yall think?

 

Maybe just a heat shield.

 

What makes you think it's the heat shield?