Check the rubber bridge loops (arrow) for brittleness, cracks or other damage and replace if necessary. To check, vigorously move the rubber loops in different directions.
Rubber suspension of the intermediate muffler
Check the strength of the screw connections on the manifold flange.
Start the engine and cover the end muffler with a rag in your hand. The engine should shut off after a short time. If you hear a hissing sound or the engine continues to run, the system is leaking.
Loud combustion sounds of the working mixture and pops in forced idle mode most often indicate a defective muffler.
Carefully tap the muffler and pipes with light blows of a hammer from all sides. Do not forget about the end sides and knock without hesitation. Blows on healthy metal sound ringing, you will recognize old metal by a dull sound.