Whenever i bought my 97 civic dx hatch, there was a real bad vibrating noise when you hit high rpms. I thought it was just the muffler so i got it replaced with a magnaflow muffler. it already had a header when i bought it. the exhaust didnt fix anything, and just made my car real effin loud. I cant figure out what the noise is, and it makes my car sound so shitty. It is coming from somewhere between the middle to the rear of the car. I think it may be the catalytic converter, but im really not sure. Please help i could use any suggestions. I took the heat shield off the pipe, so its not that. thanx doods

 

could be the cat that stuff can get in there and make some nasty noise