I keep having an 02 sensor throwing a CEL, and I've even replaced all 4 of them. So, did a little research about how to identify how to define if a catalytic converter is bad... the first test I read about is the input temp (with an infrared thermometer) should be about normal operation temp, and the exit temp should be considerably hotter. Both cats on my car are almost 100 degrees COLDER on the exit side, which from what I read means they are done.

Now, I had a death in the family and have been sick, was hoping someone could double check my logic and see if anyone else has worked a situation like this recently. The car is an 06 GT, has about 80K miles on it. Runs great, gets extremely crappy gas mileage. I had a custom tune on if from Bama Tunes, but took it off to see if I could diagnose this better. Should I just look to get an Xpipe with cats and replace the whole thing? If anyone has any suggestions, let me know. I don't want top of the line racing exhaust, just something similar to stock that might have a liiiitle better sound/performance.

 

Yup, it does sound like your cats are clogged 'cause they should be hotter at the rear. Your codes are probably from the downstream O2 sensors.
You could either cut the old cats off the midpipe and have new high-flow cats welded in place, or buy a whole new catted X-pipe. The latter will cost considerably more to buy and ship, but will cost less to install and will look neater.

 

Thanks Dino, a little confirmation goes a long way. I see a Magnaflow set that is bolt on, which is what I am thinking...