I just got off of the phone with Kolak and Magnaflow.... Magnaflow stated that although the muffler is one of their quietest and largest they have never heard of a "whooshing" sound of air coming out of an exhaust. Kolak has sold hundreds of these same mufflers for the 4.7 and had personally driven many with the same exact setup I have without ever hearing the whooshing or air rushing sound. He seems to think that there is some type of restriction in the exhaust whether it's some slag from one of the welds or something that is causing this sound. There are plenty of you tube videos with the same muffler. It is an oval 11x5x22 magnaflow. I think I may take it back to the exhaust shop and have them check into it to see if there are any restrictions causing the sound. I'll keep everyone updated.
2006 Jeep Grand Cherokee, 4.7L V8, QTII, 2" Rough Country Lift, 265/70/17 Nitto Terra Grapplers, Magnaflow muffler w/ resonated tip