They reduce emissions significantly. Little to no performance loss. It is legally required in the US and without them, it may be difficult or impossible to get the car legally licensed. Personally, if I can be ‘green’ at such a low price/performance trade-off.... I say its a good thing. At my age, I remember all the smog alerts in So.Cal and hardly being able to see the mountains just 10 miles away. I remember the big time stink of unburned fuel getting dumped into my breathing air by the adjacent cars at the stoplights. I remember the single digit gas mileage. I remember the oil burners. Yup.... smog equipment and testing is a good thing. Imagine that - the sky is blue. When I was a kid.... they were gray with a tinge of brown along the edges.
Do old after market cats on a BBi reduce emissions at all. A well running BBI would pass an emissions test for cars of that era sans cats. Well running Classic cars emit negligable emissions overall..
I think my 1976 AMC Hornet was one of the last non-CAT cars. It had a ring to keep the leaded fuel fill nozzle out, but no CAT. I think by 1977, almost all cars manufactured in the USA, or imported through regular channels to the USA would have had CATs. Pickups? I don't know about European grey market cars. Whether anybody will care about a CAT would depend on the jurisdiction. Here, if it is a private in-state sale, there are no inspections required. 100 miles north in Portland, they have smog checks every 2 years. A missing CAT likely would be an automatic failure. Some jurisdictions cut off SMOG checks at about 25 years, others may only do ODBII compliant cars. Others go back to 1975. https://en.wikipedia.org/wiki/Vehicle_inspection_in_the_United_States#Jurisdictions_requiring_periodic_vehicle_emissions_inspections I agree, many "classic" cars are driven, say less than 5,000 miles a year, or even less than 1000 miles a year. A bunch of them would add up, but other than the occasional 25 year old beater, the classics are really a minority of what is on the road, and make up a very small minority of the miles driven. I would agree that a well tuned car should have no visible smoke, but I'm not convinced it could pass the SMOG test without proper emission equipment.
boxers were all grey market, none were manufactured with cats ever. Most states besides Cali have a 15 or 25 year cutoff on emission, to the extent they test at all. In Fact in the era of obs2, around since the early 90s an emissions test is supluferous other than as a big brother oversight and money grab. Obd2 is testing emissions continuously. a bbi is injected and I know for a fact that without cats it will pass emissions standards for the early 80s. I think we agree most cars pre 90 are By now clunkers and huge emitters, in that context an old injected Ferrari may not be that clean by 2020 standards but compared to other 79s cars it’s gong to be really clean. if you have a car from the 80s manufactured with cats odds are those old cats are clogged and collapsed and the motor is therefore straini g against the restriction and spewing. it’s ironic that that early USA cat Cars Of 1970s had Correspondingly low compression motors and were so fuel Ineffcient with their then emissions equipment, that while ppm was not bad total emissions was pretty horrendous at 10 mpg. I think a 1976 Cadillac with a low compression 500 cube motor barely put out 200hp and got maybe 8 mpg, so total emissions load was horrendous even if the single cat made a Ppm measure seem ok. Unless that 70s car is still in perfect tune now with a new cat it’s emissions by any measure are horrendous. the emissions from a properly running bbi are going To be fractional of that.
