Don...thanks for the continued help on this car. I appreciate it. I'm kind of relying on you at this point because you have been responding to my posts regularly and seem quite knowledgeable about these cars.
Here's my question for you.....I'm a senior with somewhat limited income, cashflow is important. I've spent already about $480 in hope of remedying the 0420 with a flex pipe and manifold and labor.
I spoke to my local muffler guy and he seems to concur that just the front cat is causing the 0420 and probably was killed by the cracks upstream.

He will charge me 1 hour labor to remove old and weld in new universal fit weld-in california cat that you shared above. $100. Cost of part is $100...so I take my chances on $200 for just the one weld-in cat or pop for the other full bolt in assembly for $426 ( I found the same part you shared but from Florida for a few bucks less than the one you found) and be done with it, but this will throw away the flex pipe and labor I already spent.

How confident are you that the $200 route will take care of the 0420 and that the rear cat is not in play? Also, I don't see any label or tag on that weld-in cat in the pic that states "CARB" compliant. Is that critical in my whacky state?

 

Looking at the bolt-in Magnaflow again, I'm curious about that flex pipe, looks like it may not flex very much. Hard to tell.

 

There is no sensor for the second cat, so it cannot cause any codes. CARB says if it came with the car it has to be there, other states don't care about the second one.

As I understand CARB cats have to have a label on them as part of the certification. I may be wrong, your best bet is to try to buy one IN California, since it is illegal to sell non CARB cats there.

I just did a quick search on eBay, I don't represent anything about them.

That Magnaflow illustration appears to be a block drawing not a photo.

 

yeah, i dont know how it flexes either. It sure doesn't by trying to manually flex it. My understanding is that due to engine sitting sideways and rocking, the flex pipe gives enough to facilitate. The new ones look like braided fuel line. I sure don't understand how they are leak proof but I'm a dummy.

 

Yeah the new Magnaflow flex joint is odd... I've got a new Magnaflow downpipe in the box that I'm not going to be using... It's federal though, not CARB.