I have a Cattman Y-Pipe and Racing pipe. I have looked underneath the car and found nothing. I took off the cross member bar and that didn't end the noise. I've had this banging or grinding noise ever since the Y- pipe was installed 5 months ago. What the heck could this be?

 

Don't know for sure man, I hear something similar everytime i get on my gas, and it happened after I had my stillen y-pipe installed. I had it checked out and it turned out to be loose parts in my suspension due to constant "getting on the gas." They tightened them up and it seemed to be good for a while. Then I guess they came loose again or I need new bushings.

 

Did you just look under the car or did you get under there , grab different parts of the exhaust and shake it. If you didn;t shake it-try it. Chances are when you hit the gas it causes a lurch which in trun caused your exhasut to sawy a bit. You can adjust your hangers on your muffler (the rubber bands) or bend the supports around your cat. Its probaly your exhaust banging.