[ChompIV]

Here is a video of what happens underneath when I start my 2004 244,000mi EX, and what I believe to be the source of my acceleration/deep engine noise.

Am I missing a gasket?

 

[Rustedwrench]

It looks like the flange on the catalytic converter pipe came loose from the pipe. It may have rusted off.

 

[fleetw00d]

There is a doughnut shaped gasket in there (#7), but the flange does look pretty rusted. Perhaps the gasket has deteriorated and actually come apart.

 

[ChompIV]

There is a doughnut shaped gasket in there (#7), but the flange does look pretty rusted. Perhaps the gasket has deteriorated and actually come apart.

View attachment 207171

exactly. Going to go buy this right now + new bolts (reusing OEM springs)

https://www.oreillyauto.com/detail/b/walker-5231/exhaust-parts-16469/exhaust-flange-12213/efc47a63d2f8/walker-1-4-inch-thick-flange-repair-kit/31884/4786399?q=exhaust+flange&pos=0

 

[ChompIV]

Fixed by using one of these split flanges: Amazon.com: Nickson Industries 17177 Exhaust Split Flange: Automotive and swapping those bolts for 4 inch long ones.