velomax

2 cats

My 1999 GMC C1500 Suburban has been having an issue with an intermittent P0430 Code but it hadn’t affected performance. The O2 sensors were changed on multiple occasions and my mechanic said the catalectic converter will need to be replaced. He has some sort of issue with aftermarket cats so he said he would look for a junkyard replacement which was never found. The gigantic muffler developed leaks and I replace it with a Flowmaster Super 50 muffler(great sound) with a 2 ¼” inlet which was slightly smaller than the OEM. The mechanic said it would not add a significant amount of back pressure and the car has run okay for years. The code began to stay on all of the time and while on a trip, the exhaust loaded up and started to backfire badly. I limped the car home and ran 2 bottles of Cataclean through with no improvement. Since then I have run three gallons of lacquer thinner through which has made the backfire less vicious but has not eliminated it and has not stopped the code. Since I am moving to a place where they do not inspect auto emissions, I am considering eliminating the cats. If I do, will the computer have to be tuned so it ignores readings from the sensors? The other option is to replace the cats. Has anyone had good experience with any replacement? Your recommendations are greatly appreciated.