I got P0421 code on 2003 Lancer OZ Rally (just inder 100k miles) and am told I need new catalytic converter - there are 2 - the front one hooked to the manifold is expensive and I see stainless so called performance headers that are around $100 but dont use a catalytic converter up front - is the one remaining converter that is in line under the car enough to keep me ok for TX emissions tests and will I keep getting the pesky check engine light if I use these performance headers. I dont want performance just looking for least cost option to keep the thing running without throwing codes. Most of the exhaust system is rotten so it pretty much all needs changing so just changing a few parts unlikely to help

 

i have an 03 lancer oz rally too and my catalytic converted got clogged and i had to take it off and still passed emissions test however when i took off the second converter i failed so in my opinion you can pass emissions test with the one under car