As long as you have all your cats a thrush welded works good it's 38.88 at advanced Auto and it's equal to a flow Master 40 and not loud at all you can barely hear it going down the road and at idle it's got a nice low tone grumble

 

I had a pair of Flowmaster 40s on my 87 Chevy truck (350) and it sounded nice, but I got complaints about the noise in my up-scale neighborhoods. Some of these houses cost 1 mil or more. I don't drive more than 25 mph on the route but they could still hear me at 3 AM. To quiet it, I stuck a pair of Cherry Bombs on the ends of the tailpipes inside some thin tubing that slid over them. I think they were about 4". I was using a pair of cheap cats designed for the 4.3 S10.

 

No those rules have been relaxed. There is a post from the moderator on that.

 

Just a heads up on the PO420 cat codes. ALL CARS have the cat converter under full warranty dealer replacement for 8 years or 80,000 miles. Federal law. Regardless of ownership or original owner.
Just got my moms 2010 honda crv replaced basically for free with the po420 code, all they needed to see was the code on the scanner and no questions asked they replaced it.
Nothing is free tho, they still managed to charge $90. for clamps and hardware. Still saved about 2g.

 

I'm starting to think my emmisions code may have been triggered by larger tires I've drove this for 2 months everything fine even after the lift I checked my milage from when I put the tires on exactly 100 miles which is enough time for the system to do a check I also have wheel sensor 1234 out of spec I'm wondering with the California emissions if I have to have pcm recalibration for that because of the lower rpm at higher speeds making the pcm think I'm jumping in fuel when I'm not because the cats are clear and the O2 sensors check out fine and are within factory specs

 

Don't think so. PO420 in my experience means the cat is plugged.
Like I said before the dealer replaced ours at no charge with no further troubleshooting than to verify the code PO420.
There are all kinds of posts stating the O2 sensor, etc etc. None are right. If the O2 sensor wasn't working, you wouldn't get a code.
One way to tell is the make a couple additives for the gas tank that will clear the cat temporarily. One is called 'Guaranteed to Pass" . I used this twice. Both times it cleared the code for a month or so. Long enough to pass emissions inspection tho.

 

Well your free or at no charge doesn't work for me fist off this is a 2000 so it's 18years old the odometer has 170k on it even though it's got a crate motor with 6k and the exhaust and cats are oem

 

That and I stated everything was fine till the 32inch tires and low highway rpms and I also stated cats are clear my backpressure is within spec and my o2 sensors are working properly my fuel mileage is the same 18-19 town 23-25 highway I may get a set of walker procats and throw on for ****s and giggles since they are 135$ a piece rather then 600-800 for the cats and down pipe or since my state requires only fed visual inspection I may just delete the Cal cats splice the wires to the down stream and run it after the downstream cat

 

You're welcome, I think.
I am aware you have a 2000 and never said you can get a free one.
I think you're on the right track to replace it. Or both as you have two.
Toss a bottle of Guaranteed to Pass in it, like $12. See if the code goes away for a month or two.

 

I've already cleared the code and dumped. 4 bottles of catyclear in it in the past week still comes back

 

So I went and got a brand new snapon obd reader/recalibration tool this one showed graphs instead of fluctuating numbers turns out 02 s2b2 had no power too it hmmm..... So I bought a new sensor plugged it in and boom check engine light gone turns out the connections were broke inside the connector but my cheapo scan tool did not pick up on that problem solved everything is in check and even recalibrated to speedo myself

 

The catalytic converter is not usually a wear item. If it has deteriorated than there should be an underlying reason, such as;

"Leaded fuel was used where unleaded was called for (unlikely).

A damaged or failed oxygen / O2 sensor Downstream oxygen sensor (HO2S) wiring damaged or connected improperly.

The engine coolant temperature sensor is not working properly.

Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe.

Failed or underperforming catalytic converter (likely).
Retarded spark timing.

The oxygen sensors in front and behind the converter are reporting too similar of readings.

Leaking fuel injector or high fuel pressure Cylinder misfire Oil contamination"

 

the problem has been solved....if you didnt read my old scanner couldnt pick up the variations the new scanner could it was 02s b1s2 it was replaced..and for fuel milage i went 848 miles yesterday cost me 87$ for the round trip for a total of 23.86 mpg highway at 65mph the whole way on 235/85/16s would of done better but the hills got me with the 355 gears i probably will gear up to 373

 

Glad you fixed it! The code is generic and the issue was with one of the underlying reasons, that is why i posted.

 

Just a heads up, 2010 CRV with 60k miles, the PO420 WAS the cat. They did not look any further at the dealership, just ordered and replaced the cat. Said they get a few a month like that. Not supposed to happen, thats why the fed mandates a universal 8 year of 80k mile warranty. The dealer would not be giving away a $2k job for $99 otherwise.