I currently have an 04 softail and I put new pipes on it (Samson Sidewinders;no baffles). when I put on the pipes at the idle it has a popping sound that is in syncrinization with the sound of the exhaust. At first I thought that it was the head gaskets not seating correctly or something but I felt no air escaping. When I cover the rear cylinder exhaust pipe the noise stopped which lead me to believe that it is an issue with backpressure. Any suggestions