when i step on it in my mustang i get a rumble noise under my car what do u think it is? i think i broke my cats or something? what do u guys think?

 

You will want to be much more descriptive so someone can help you. Give as much info as you can regarding where the sound is, what it sounds like, etc. Can you make it stop, does it go away or is it always there?

 

i posted another posting check that one out plz it gives more info.....