I had to pull my exhaust system to replace a $3.00 seal on my 2001 Getrag. Now that it's out, I'm wondering if I should try to clean or replace the catalytic converters or just leave somewhat well enough alone? Reason - car and cats have 200K on them. I rebuilt the engine and it 'seems' like it has less power than before and it is definitely getting fewer mpgs. Both could be cat-caused? Cleaning - At youtube auto university there are videos about cleaning cats. Scotty Kilmer takes a cat and puts it in a bucket of soapy water overnight. My cats are permanently attached to the manifold pipe so either cleaning or replacing would require me to cut them from the pipe and then reattach with clamps. Does anyone have a comment on this job thinking?