Kinda hard to prove it was the shop’s fault if it doesn’t match up. For instance, I could have had a cat on the car going into the shop and taken the cat off after passing. (not that I would do that).
The newer catalytic converters do not create an exhaust obstruction. They are a ‘honey-comb’ design and you can almost look right through them. The older ‘bead’ type could get obstructed though. The newer cats are actually less of an obstruction than a muffler.
The odd part about all this CARB sticker nonsense is, the car was “smogged” with non CARB legal parts in place and actually ran cleaner than stock.
Some of the earlier legal replacement parts didn’t have EO/CARB numbers stamped on them. This is a problem for my old truck(have to keep the paperwork). Many performance parts will also make the vehicle run cleaner. The whole CARB thing is really screwy. Do you know that it is not legal to switch a emissions regulated carburetor car over to fuel injection, even though that does significantly reduce emissions and increase gas mileage. It is ‘tampering’ with the existing emissions equipment.
The initial ‘premise’ on how the emissions laws were written, was that the manufacturers could get a cleaner running car than most anyone else. This is contradicted by the fact that there were many advances in the technology that US auto manufacturers declined to put into production. There were people back in the mid/late 1920’s that were building dual overhead cam versions of the Ford model T engine (which is an flathead or L head). Oddly, one of these were “Louis and Arthur Chevrolet”, called the “Motel T Ford Frontenac”. Others were Jack Gallivan (Model T Gallivan), Harry Miller.
It took the Japanese producing overhead cam and fuel injected engines across their models lines, for technology to be placed into production by the US manufacturers. The US manufacturers ignored the German cars (which also had the tech) because they considered them ‘fringe/specialty/luxury’ cars. (Mercedes Benz was using OHC in the late 20’s, early 30’s)
