Good Afternoon guys,
I have a 10' GT that is throwing a P0420. I switched the O2 sensors when it first happened a few years back, but now it is coding again. My mechanic said it is more than likely that the Cat is on it's way out. My question is, should I simply get a new Cat (~$1100) or get a new catted downpipe ($600 Invidia) and go from there? I've read that most have overboost issues when they upgrade their downpipe. Looking for advice/suggestions.
Currently OTS Stage 1 with an Invidia catback.