Here is the view inside the 24216 muffler. It is straight through, and is remarkable that it reduces noise as well as it does.
I mounted a Radio Shack sound level meter on a camera support arm so it would be in the same location for before and after testing. It was mounted near the center of the windshield. At 55 mph on level ground, I would floor the accelerator and read the sound level. It was 2 - 3 dBa quieter with the muffler.
The Walker would probably be quieter, but I still want my truck to sound like a deuce and a half, just toned down a little.
BTW, I have a D turbo.