I guess its just a personal preference. But I think the 50 series SUV muffler is great on the 4.7 liter. It has a mean sound to it and its not raspy at all. You dont get that loud interior drone like you do with the 40 or 44 series and can actuall carry on a conversation while driving..lol Not to mention how many people that have come up to me saying how great it sounds.