IIRC the now CA only cats are identical to oem replacement cats. The oem ones have always been much more expensive than the after market ones(usually 4-6 times), and as w/most oem Toyota parts, you pay more for the better quality. If you ever compare an oem cat to an after market one, while they don't appear to be that different in overall size, the catalyst chamber is less than half the size and they weigh about a third as much. Given the size difference it is likely that the universal catalyzing metals burn out quicker and w/age tend to not get hot enough at idle to work properly.
Here is apic of a stock cat from my '90 3.0 and the hi-flow magnaflow one I have.
The "X" represents the size of the burn chamber from screen to screen.
In Jan '05(7 mos. of use) the Magnaflow I have on my '90 passed the smog test,. The HC's were a little high for both tests, but w/in acceptable amounts. 2yrs later in '07 it passed the 2500rpm test, but failed the idle test by about 20 HC's. W/an adjustment of the idle to 1050rpms, it passed. In '09 it failed again at idle even w/the idle speed at the highest allowed. Looking at the smog reports from years past, and the dramatic increase in '05 I had an idea it was the cat. Fortunately since I tend to keep anything that can be still be used, I still had the oem cat. I installed it went back and passed w/only 30HC's at idle. I was able to set up a w/the tech time to check the cat after the shop was closed to see if the cat worked at all at idle. I got off the freeway and went to teh shop, w/o having to wait to be tested the cat passed at idle, not as good as the oem one, but still passed. It appears that the smaller chambers cool down too quickly to be effective under most testing conditions. I am still running the magnaflow, and will install the oem come test time.
$100+shipping from the site posted isn't bad for a CARB approved one, it is a far cry from the $376 price listed at Magnaflow, and I paid $160 for my universal magnaflow locally in '04. If suppliers aren't prevented from shipping non-CARB cats to CA and going to install it yourself, I would just order a universal replacement cat from Summitracing.
great write up. I have a new magnaflow cat that is made for 5-6 liter vehicles as a secondary cat... and im pretty sure this is why i keep failing the NOx test. And im pretty sure its not enouph for my older 22re. So i have a carb approved cat made for my truck on the way for my next retest.
