I have a little first hand experience with mufflers on the 5.9s... I cut out the stock muffler and put in as Flowmaster Super44 and it was aggressive once the exhaust system warmed up but it just wasnt loud/mean enough... replaced it with a cherry bomb extreme and at idle its really mean sounding and I love it when I start the truck up (turns alot of heads)! As for driving, the extreme puts out a loud but deep growl from 1000rpms-2500rpms. After that it gets quieter the higher the rmps go up. Super 44 did the same but it was all around noticeably quieter
Have a pratically new super44 for sale!