Contour Enthusiasts Group Archives Forums General Troubleshooting How can i prove that my cat is bad?

A reputable mechanic shop can perform a backpressure test using a special pressure gauge made to hook into the exhaust pipe. The gauge is hooked in through a small hole drilled into the pipe before the cat, and after the test is complete, you pop in a special rivet that seals that hole. Anything more than a couple a p.s.i. during a roadtest under load, would indicate a restriction in the exhaust