I'm planning the next wave of fixes/upgrades on my 85 DeVille with 4.1 and am looking at exhaust upgrades in this round. I am wondering if it makes sense to replace the catalytic converter, under the assumption that my 22-year-old unit is probably getting worn out, and also under the assumption that there has been improvements in technology over the years.

The car has always failed emissions testing on first try, every time, in both Calif and Tenn. In a couple of cases I was able to just blow out engine gunk on the highway then come back and pass the test. Sometimes I had to have a mechanic tweak the engine. I don't know if my C/C is acting up any (I don't smell it) but if a better C/C would help me get emissions lower that would be a good thing.

The smog pump was replaced last year after it seized up, I'm guessing a stock replacement was used.

I am planning to put in a high-flow exhaust to get some better engine performance anyway, and replacing the C/C would not be a prohibitive increase in cost or time. The question is if I should even bother with it at all.

Thanks!