Just installed cat back system on my 95 dx. Everything was fine for a couple of weeks. Now every time I run the car when it gets warm I hear a loud ping noise, not very often then when I turn the car off I hear it again a couple of times. Checked all the bolts on cat back they are tight. Could it possibly be somthing to do with the manifold.

 

maybe just the car settling. just like a house settles at night.

but if you hear the pinging when you are running the car then thats another story. when you say you hear it when the car is running do you mean just idling or wat?

 

It's probably just chemical reactions taking place within that cat after your car is turned off. It's just more noticable since you have an after market exhasut and not the quiet stock one.

 

its just settling down (cooling)
when you heat stuff it expands. when it cools it shrinks back to normal

 

Well it doesnt happen until the car gets good and warm, and yes i do believe it has to do with heat also. But I was just curious about what it could be.