I have 2003 lancer OZ, my cat is almost gone giving me P420 error...i was thinking changing the headers along with the catalyic converter the only questions arise...right now i have Cat where the headers are suppose to go...if i can fit a custom catylic convertor when i put RRM Headers...or better question should be what route should i take keeping CAT and Headers in concern.....
thanks for your information in advance

 

I don't know what the emmission rules are in your area, but most people just remove the upper Cat. when using headers. (There are 2 on the car)

I did this and never had a CEL problem once I reset my ECU. I was also running a RRM piggyback.

 

hes correct, there r two cats on our exhaust, 1 is in the header, other is mid stream before the midpipe like on most cars.

a set of obx headers will replace and delete both of them.

i used those for a while. worked fine and fit perfectly..
i dont know your emission laws, but i dont have any in alabama. so if u get inspections on your emisions in your state u will not pass without cats.