In my late teen years I worked for a muffler manufacturer and learned a lot about back pressure, exhaust scavenging, decibel levels with different muffler lengths, internal diameters, placement of the mufflers and resonators in relation to the head pipes, such as the further back the mufflers are placed, the better job they do lowering noise. How an H-pipe ( this was in the late 60's, early 70's) affected scavenging, lowering back pressures, equalizing back pressures and sound tone.
I currently run a TTI ceramic coated system with the X pipe in my wife's 5.9 Magnum 73 Challenger.
She loves the exhaust tone, but also like to hear her stereo tunes.