A proper working cat needs the exhaust mixture to cycle from lean to rich, back and forth. Rich enough to get a little fuel in there, then lean enough to get a little oxygen in to burn it off.
On a late model car this can happen several times a second
Allen
Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first.
Life was a little easier when I was just a wrench.
