I have a question for you guys. After I shut my car off I hear a ticking noise that seems to be coming from the cat converter. It sounds like there are tiny stones or something bouncing around in there. Could that mean my cat is getting plugged up or am I worrying about nothing. Thanks.

 

mine does the same thing. somebody told me that means it's crapping out. i guess it's the stuff in there breaking up.

 

Yup, its breaking up in there. Time for a CarSound or similar high-flow replacement.

 

Thats what I thought but now I have a good reason to get a new cat I will also do a 3 inch catback while Im at it. I will do headers later on. Which cat is better- carsound or catco? Also which is cheaper? Would you happen to know the part # for the the carsound cat for 86-90 applications? Thanks.

 

They are both good, but I *think* CarSound flows better.

 

Another thing is could be is when you shut the car off, the cat starts cooling and the metal of the casing is shrinking. This is also a sound found with new exhaust. My car does it too (fairly new) and I have no cats. Mine makes the most noise around all the welded joints. I would assume due to welding changing the metals structure slightly makng it expand and contract at a different rate the the rest of the tubing. I'm not a metalurgist so I can't technically explain why it makes the noise.