I have an 07 NBS GMC Sierra 5.3 I am changing my exhaust soon since the women is buying me a new muffler for fathers day. I am either getting a super 44 flowmaster or the American thunder series which after alot of researching I believe is the super 40 flowmaster muffler? Has anyone on here had the American thunder Kit on a 5.3? I am not running duals since I think the NBS trucks are more of a less is more body style vehicle.