the largest volume case will be the quietest.

magnaflow has some 5x11x22" case mufflers. they also have some 5x8x24". the first might be slightly quieter due to the slightly larger volume.

1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)