I have a bad cat for sure on my '99 3.9L (P0420, O2 sensors mirror each other, just fixed years long valve seal leak).

Trying to figure out my options.

Is anything aftermarket from Rock Auto gonna be worth a damn? Seems aftermarket is never really the way to go, but there's no OEM option is there?

Am I better off just straight piping the cat (keeping the muffler)? I have no inspections where I'm at, but is there a way to do that and have no check engine light?

Junkyard?

What would ya'll do?

I wouldn't care that much, but it does feel like the truck could breathe a little better than it is, and the CEL annoys me.

 

Magnaflow makes some good high flow direct replacements. At least, they used to.....

 

Being a 99 you should only have one main cat. I put a Magnaflow cat on my truck.