I just got done installing a new Random Tech cat-pipe and a Bosal flex. It went pretty good, but when we got done we had an exhaust leak at the manifold. We worked on that and thought we got rid of it. When I got home I noticed strange noise at low to medium rpm's. It's kinda like a rattle or vibration. It's really strange. It's hard to describe. Has anyone else noticed any strange noises with a Random Tech cat?