Originally posted by Ken300D
They can be cleaned with a tire iron. It really restores them to their like-new flow rate or better.
Ken, do you mean by banging on them? I recently had the exhaust replaced on my 300E and the clutz that did it beat on the tail pipe of the cat trying to get the muffler off. He finally used an impact chisel to do it.
After he was done, the exhaust system was noisier than before despite the new OEM muffler and resonator. I assumed he damaged the cat but it passed the emissions test.
There are two kinds of cats, ceramic honeycomb and ceramic beads. Beating on a ceramic bead type might work but I would think it would damage the honeycomb type.