I noticed when the car gets warm and I'm sitting at idle I get some noise from under the car, sounds like metal hitting on metal. Leaves me to belive its exahaust related, any one ever had this before?

 

I have had that exact same sound from under my car, I couldn't pin it down . Thought it was tranny because it was comming from around that location. Turned out to be the cat because I after I ditched the cat with the long tube install I don't here it anymore. Might be caused by the honeycomb material inside it getting loose and rattleing around.

 

Thanks man, its the original cat from 93 on the car