Different exhaust heat/pressure

Hey guys, I noticed that one side of my exhaust has little to no pressure coming out of it and is just radiating heat out the pipe end. This would be my cylinder 3 and 4. The other side feels completely normal in that I can feel the cylinders firing creating exhaust pressure each stroke. Cylinder 3 and 4 plugs show that they're running a bit lean but still firing and burning rather correctly. Any idea why this would happen and how worried should I be about damage being done to something?
Thanks guys!

Maybe it's restricted? Pics?


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Rusted and collapsed muffler innards?
Please put your bike info in the signature line.

I've pulled the exhaust off recently and everything was solid so I very highly doubt it's anything blocking the exhuast. My bike is an 83 kz1100 shaft. I adjusted my valves recently and everything was in spec too