After installing the mil eliminators on my 00 gt and clearing the code... every few weeks (probably 3-4) the light will come back on with the same code. The code is P0430 catalyst system below threshold bank 2. I got a second set of mil's and put them on... same result. I am wondering if because i ran the car for a few weeks without MIL's if it somehow fouled the oxygen sensor and i need to replace that? Anyone have any ideas?

the setup is a borla cat back with a bbk offroad x-pipe.

Thanks for any input. Much appreciated.

-Steve