Bad Catalytic Convertor ?

What are the symptoms when it is bad?

after running for a while it will glow red hot!!! real low pressure out of tail pipe. no real test to check them.

There is a test where after running for a while they can check temp of pipe before & after cat with a temp gun. Why do you ask? Having particular problem? I just had to replace mine recently b/c it wouldn't pass emissions test. Good Luck!!