I know this question pretty much answers itself . I fear my main and only cat is starting to clog ( after at least 700 miles with air pump removed. ) As stated I'm pretty sure that is the case . My symptoms right now are cruising afrs . I can hit 18+ cruising . BTW I'm s4 motor and lim with s5 uim . I'm keeping the cat on until I can weld a bung into a flanged resonator pipe for my 5/6 ports . Anyways back to my issue . I can run 1-4 shifting at 4k with afrs at 13.1-14.9 once I'm in 5th at 55-70 cruising my afrs spike . I'm attributing this to the most likely cat blockage and resonant heat involved . Am I wrong in this assumption ? I'm thinking of punching all the ceramic and build up and blowing it right out so the cat becomes more of a resonator . Any one have input or ideas on this (besides putting on the air pump and acv ) will be greatly appreciated

 

Take it for a drive and see if it becomes red hot, that will prove without a doubt that it is bad.
As for gutting it, just smack the thing with a hammer if your too busy(or lazy) to take off the exhaust

 

Yeah, if it doesn't have adequate oxygen supply it fouls pretty fast.

Replace it with a resonator as a straight pipe will make you car sound like an angry chainsaw.

 

I punched one out a long time ago. Messy, but not the hardest thing ever...

 

baseball bat plunge..

 

^my favorite technique