so I was drving my 98 Formula on the rough road and I hear a loud rattling noise over many tiny goops ( little bumpy on the roads) old road. and it rattles it enough to oversound your stero lol I checked there is no rattle snake in my car. and I checked the muffler and nothing wrong with it so I checked all muffler mounts. they're fine, so I check it and nothing hitting some where under my car so i dont know what it is. once ur on the smooth road u wont able to hear it. if you put like 2 inch rock on the road and you drive over it you will hear a thing... still tring to finding the noise tho....

thanks
Maamorth

I guess the noise is coming from the bottom of the car?Maybe a bad cat?

It's kinda tough to diagnose a noise over the internet so I'll leave this here until you can further narrow down where it is coming from. Then if it's not inside the car I'll move it to the appropriate section so you can nail down where exactly it is.

I noticed when I had my 6"'s out of the sail panels that the speaker clips could easily fall down inside the speaker houseing area and are UNREACHABLE by any means. Possibly a previous owner dropped something in your sail panels and its rattleing on the inside of your car ... just a possible suggestion you could check out.