Catalectic converter - Delete or Replace?

[velomax]

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.

[KARNUT]

30 minutes ago, velomax said:

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.

The only experience I’ve had with a cat was on my 94 Z-28. The cat clogged with power reducing with no codes. My exhaust guy put a glass pack in place of with no codes with the cat removed. Power was restored. I did have a 92 Chevy Truck with a blown stroker that had 2 after market performance cats that were trouble free. Don’t know the brand. I had that truck 12 years.

Edited October 8, 2023 by KARNUT

[richard wysong]

It is illegal to sell used cats unless they are recertified. A clogged cat shouldn't cause a back fire out the exhaust, that would be caused by unburned fuel and a leak to introduce enough air to allow it to ignite, Sounds like you may need another mechanic. Do you have 1 or 2 cats on that?, an after market cat should be fine but be aware cats do not fail on their own, something causes them to fail such as running rich or lean, oil burning etc

[velomax]

2 cats