ponyboy302

this is about the car in my sig ... in 4th gear at 2500 rpms if i tap on the gas ill hear a slight buzzing and after about 3000 rpm it goes away .. i used to have a 89 with the tailpipes coming out of a cut out bumper ghetto style just cut a reverse u in the bumper but anyway its making that same noise of the tailpipe hitting the bumper .. like my exhaust is loose .. as far as i know the whole exhaust was done about a year ago .. i tried wiggling the tail pipes and they dont budge .. could it be anther part of my exhaust or something else ? any ideas ?
s**t thought i was in gd please move if necesary