There is some in-car video from autoblog showing (amplifying) the exhaust drone in the car. The sounds that we are hearing is similar to this one when the in car video is playing. Note, the audio quality is really poor on the microphones so the Drone IS REALLY REALLY loud in this particular case. The more videos I see the more I think and feel that the exhaust drone is part of the vehicle and in no way is a design flaw.
HP AutoWorks, can you chime in and let us know if you are hearing similar droning in your car following your mid-pipe modification?
http://ca.autoblog.com/2011/05/26/bm...t-rs-on-track/