What is considered too Hot for Roe Oval Cats

[JimT 99RT]

Sean or other tuners jump in and tell me how to tell if my Roe Oval Cats are too Hot? The A/F reading before the Cats looks good 14.7-15.5 under no load at idle, and at full load A/F is 11.5-11.8. I have stock headers, Roe Oval Cats, and a Borla cat back exhaust. When I pulled up to the Muffler shop to have O2 bungs welded ahead of the Cats, the welder stated he thought my Cats were getting too hot. I have a Roe S/C and am running a 7lb pulley.

 

[Sean Roe]

Hi Jim,
"What is Too hot?"
To operate properly (burn fuel), they will be in the 900 degree F range when running. When running a blower, the increased a/f ratio under load will make a catalytic converter hotter.
A stock cat is far more prone to overheating as the exhaust gets hotter each time it goes through a substrate (stock has 4). Overheating a cat leads to substrate failure.
I wonder if the welder saw the normal (for a Viper unfortunately) dark area in the side sill insulation. When we take stock cats out to replace them, it is common / expected that we will see the sheet metal of the insulation cracking and falling apart near the cat.
No cats is the coolest option.
Hope that helps.
Sean