You guys with V8s, if you're going to replace your cats, I would take that opportunity to add LT Headers and Y-pipe with high-flow cats... Don't forget to replace motor mounts while the exhaust is off if your car is close to 100k or more...

As for the rear O2 sensors, you can replace them, tune them out, or get emulators... Choose your own adventure.

 

Car is in Cali guys so LT's are probably a no. I'm leaning towards replacing all 4 sensors and the cats. I've had a MAF that was getting a bad reading causing my o2's to say they were bad, replaced the MAF and the codes went away.
Correct me of I'm wrong, but if the front o2's are getting a weird reading they will tell the computer how the car should burn gas?? So really it might not just be the cats if I'm right.
On a side note I still think your tune sucks *** Cody lol

 

The o2's simply read the a/f content basically. If they get a high reading then the pcm will pull fuel to lean out the mix, if it reads low then it adds fuel to the mix.

The smell is usually the CATS, and since it's in Cali you will need those and all your emissions. LT's won't work for you but I recall some saying they can get by with them. Mids or shorties would be the only thing you could do in Cali and still pass emissions I think.

 

Last I checked no mids cause they move the cats, shorties or stock exhaust manifolds

 

Are shorts smog legal tho? Do they have carb number?

 

Yep, just look on summit for edlebrock ones and they'll pop up

Here ya go Edelbrock 65733 - Edelbrock Shorty Headers - Overview - SummitRacing.com $387.95 and they have a carb number. I'm going with shorties for my build, gettin a state ref ticket isn't worth it

 

Where is there piped natural gas in the drive train or exhaust?

*Edit. Unless you mean the exhaust itself

 

Don't try to make sense of that natural gas statement, I think he's a spambot.