I am interested in a high-quality catalytic converter - that is, one that is highly efficient at catalysis. I want to install a modern cat onto an older (1987) car. from browsing after-market parts which are claimed to fit my car, there is very little I have found besides glossy advertisement-style information as to what makes a catalytic converter good at its job. frequently they make a big deal about the warranty. also, the shape alone sometimes appears to be completely different from the one on my car.
so what parameters can buyers look at to judge what a good cat is?
how about refurbishment of an old cat? can not the old junk in there be blown or rinsed out at an appropriate shop?