I removed the 2nd Cat and shined a light through it. Every tiny little hole was open without any buildup at all.
The Cat internals were made of a hard mettal compound. Not ceramic made like I'm used to seeing. I jammed it with a rod. No luck knocking it out. would be better to get a straight pipe replacement if this area is the issue.

2002 4dr Kia Sportage 4X4
Tires:235/75/15, Wheels: Black 15x8 Steel ProComp 2.5" B.S., Hubs:Warn Manual, Lift:3" UPYOURKIA, Trailer Hitch, Cargo Rack, Clinometer.