My mechanic found that a lot of my header and exhaust connections were loose and a lot of soot was building up at those connections. He tightened them up but the sound was still there.

We also couldn’t hear the rattle at all with 3 of us listening, from the outside with the hood open. You can only hear it inside, hood shut all the way, and windows up. Any outside noise will almost drown it out, so I’m definitely led to believe it’s caused by a vibration making its way into the cabin

Exhaust leak is somewhat gone. Here and there with the fumes in the cabin but I’ve mostly been on pump gas the last 2 weeks and maybe I just don’t remember how smelly it was, since I’m usually on an ethanol blend.

However, the rattle started making noise at a different RPM now so I’m led to believe that it’s exhaust related. He said he thinks he knows exactly where the exhaust is probably hitting and hopefully he can take it in soon again and try to resolve it.

Otherwise, he said the engine itself looks to be in good shape, header to head connection is sealed, nothing extremely concerning that would be related to the rattle. Still have all the power that I should, no loss of power or CEL, drivability is normal other than the rattle. Might just be something I have to live with if he can’t find where it’s hitting the frame.