OK wait... you were having problems with a CATTED x????? I missed this tidbit, catted, highflow should not be throwing codes by right... unless
BBK isn't meeting emissions standards with the cats they ship with the product...
BBK is right, there should be no codes being thrown... bad cat or bad o2 sensor is my honest guess... Or this is a 96-98 correct? with 4 cats from the factory? I guess its possible to throw a code going from 4 to 2 high flow, but I honestly can't see it.
Even with my catless prochamber w/out eliminators or a tune it won't throw a code for ~400km if its warm, 150km if its cold (sub zero)... /W tune it will not throw a code (obviously).
Mil eliminators are NOT guaranteed to work. In 85% of scenarios they seem to, but I know of people who they haven't worked for.
I am with BBK on this one, I feel like there is a puzzle piece of information missing...