I had the ACR-X headers with high flow cats installed on my 09 without the Mopar PCM. Ran without a CEL for around 2100 miles. Then it would pop up, especially at times when I was stuck in traffic, etc. If I kept the cars rpms up and driving at normal speeds, not too much of an issue.
I firmly believe the issue is with the aftermarket cats, they are a disposable item. You will get "X" amount of time on them, then they start to degrade. Sorry, they just aren't able to last like the stock (heavy and 3 times the size) system does. Just budget for new cats if you want to run them and run clean. I now have two exhaust systems, one with the cat and one without a cat. I also now run the Mopar PCM....no more CEL's regardless of which system I run.
FYI, after I installed the headers and hi flow cats, I had the car smogged just to see what the numbers were. I was within 1-3% (IIRC) of the cars stock numbers when it was new (had to have it smogged when brand new since I bought it out of state). In otherwords, it would have passed California's smog test with flying colors. I posted the results on the forum, I think about 3 years ago. Visually it is not smog legal with headers and a single cat, but how many smog techs know exactly what kind of exhaust manifolds a Viper uses?
George