i have 2006 f150 5.4l xlt 140k miles my left cat is clogged driver side and im trying to run through my options. since im in california both cats would cost me around 3,000 plus labor. i was told i can get after market cats from out of state that would pass smog technically speaking numbers but would fail due to carb number. then theres just deleting the cats & tuning my a/f ratio which i do not know how to do o know anyone who does. im wondering long run whats not only best for my engine but cost effective. 4,000 for cats replacement would bury me financially and i dont really want to let my truck sit and rot.

 

If you are in CA, you have no choice. You need CARB-legal cats.

 

I have an 03 with bad cats in Cali also. I did a bunch of searching and there are after market cats that are legal in calif. If you search the state sites that deal with smog you can find a table that will direct you to the ones that are legal for your truck.

Mine from Ford was about $1500 per side (4 cats total) and I think the aftermarket ones were about $4-5 hundred per side. Sorry I don't remember exactly where I got this info because I just parked the truck and bought another for work. If I can remember where I got it, I'll post it up.