I just ordered Flowmasters 50 Series HD that was designed for our 5.7 HEMI engines. I had a super 40 on my 04 Hemi and it performed great but talked to a couple diff people 2 from flowmaster and 1 from dodgetruckworld saying that the 50 series HD part # is 9530560 would still make more HP and TQ over the super 40. So with that said I got one. Im looking foward to see what this muffler will do in letting the engine breathe out better. I got a K&N intake and just switched to Full Synthetic Oil and see what these 3 mods will do for performance. Anyone running this muffler. Im thinking of doing something before the passenger side rear tire. Will try to get pics.