Sheesh... all cats are not created equal...... It is not a simple matter of "stacking converters". There are single bed, dual bed and even triple bed catalytic converters in production. Each bed contains a different catalyst (remember this term from school?) that causes a different chemical reaction. The available space, the design of the available space and the engine displacement all have a bearing on the size, arrangement and number of converters. If you want to see convoluted, look at the (IIRC) GM HD5 system.... these boogers got HOT. Then there's GMs cat after the mufler systems......
Let's remember that it's not the manufacturer that's creating vehicle emissions,,, it's we drivers that are taking care of that (where'd this smog nazi s*it come from... the rest of us have to breathe this air too).
Lastly, I have seen the idea of "meticulous care" include weekly waxing yet forgetting oil changes. But, when things go wrong, we an always shift the blame....
Jim Warman snipped-for-privacy@telusplanet.net