Originally Posted by ByThaBay

Actually those codes can be due to exhaust leaks around the cat. Often the aftermarket HFC uses the triangular flat style gaskets which will almost always leak. I would suggest checking for exhaust leaks between the header and the cat - the past 2 people who came to me with those codes had stock cats that someone had re-installed and they didn't use oem crush ring gaskets and leaks developed causing the codes.

Send me a message if you would like me to review the logs from the tune and help you narrow down the problem. Leaving this issue will result in the ruined cats because the ecu will add extra fuel to light-off the cat to reduce emissions. I'd suggest digging in and solving the problem or at least gaining confidence in the cause.