I recently cut open a secondary cat that some guy had tried to gut, apparently using something like a crow bar and a sledge hammer.
These cat cores are made of metal, so that his efforts to break up the core simply bent it all into a metallic lump. Presumably had the core been ceramic, it is brittle enough so to break up into small chunks under such crow bar force.
My original question was out of curiosity, simply to wonder if the manifold cats were also made of the same metallic construction.
Seems to me that a ceramic core would hold up better under the higher heat exposure so close to the engine.
Thanks - DM