[xj-s] Cleaning a catalytic converter

I have the secondary catalytic converters from 95 4.0 removed to have a dent taken out of the pipe and make the pipe better fit the aftermarket primary cats. The engine side honeycombs are probably 50% blocked (viewed with a flexible cavity camera). There are gas tank additives that claim to clean catalytic converter’s but that’s snake oil. With the catalytic converter removed, is there anything more real I can do?

I guess the first question would be what is the clog material, and what solvent would break it down? In all honesty it looks white but the glare of the camera LED can alter colors. The honeycomb on this car is not visible with the naked eye, and the pipes snake in a way that makes bashing the honeycomb out much more difficult than on a V12. The two catalytic converters closest to the engine (paired) were already replaced due to rust out.

All google results are gas tank quick fix methods/myths.

The resulting functionality of the catalytic converter after cleaning is only a secondary concern.

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