I called GSM the other day about something to help dump a PO430 code I am getting on a Hemi Ram with headers/high flow cats. There is a box that can possibly do this, but the price is crazy. I was also told we can space the O2 sensor up and out of the main exhaust gas flow and it may cure the code. Due to the location of the O2 bung on the truck, I am going to look for some proper sized washers and try to pull the O2 sensor up out of the main flow. It apparently does do the trick for some other makes with high flow cats on them.
GSM also told me the shop 300C SRT8(JKetrons old ride) is setting a PO420 or PO430 code(same code, just different sides) with the headers/high flow cats.