Quiet High Flow Mufflers?

[Goat Blower]

I did some research on this last year and basically I came up with the fact that the larger diameter the muffler, the more noise suppressing material is in there. So even a 3" straight through muffler with a 6" diameter can will be much quieter than say a glass pack.

I'm looking for the same thing with my build this spring. I went back to a 3" system comprised of a Thermal cat back, but it's way too loud for what I want, so I'll be looking for a good quality mid muffler in addition to the rear muffler the Thermal comes with. Either way, with at least 3" piping and a good quality muffler, there really shouldn't be much restriction in it.