Originally Posted by Jamie@dundonmotorsports

In general no you don't have cat codes with our parts. Need to check for air leaks, loose clamps etc. If the car has lots of track time on it, doing new O2 sensors at the same time as install is wise...

If you purchased the refurbished headers from Dundon then they carry a lifetime warranty. Anyone that purchased a new system from us has a lifetime warranty. Many many track miles driven, without issues on our own cars, local cars, international cars etc... O2 sensors don't last forever, they too can contribute to issues. Best way to handle these situations is to reach out to us via email or phone. a Rennlist comment isn't likely to be seen by us, nor do we know who you are or how to help...