Dave I looked at their site and figure that the main jist of their mufflers is very little back pressure, like a straight pipe, but still good sound muffling. Their mufflers will still have a natural frequency but who's to say at what RPM the exitation will happen at. Spintech could test them and find out what that frequency is but it would be a waste of time since as soon as you start connecting pipe and installing hangers that frequency/RPM that the exitation occurs will change either up or down.
I do have a problem with the term "sound vibration energy". I think what they are trying to say (in all the gooblygoop) is that the sound you hear is caused largely by the molecules of the exhaust gases bouncing into each other in the piping and the muffler components and at the same time making heat (the heat part makes sense). They then incorporate space age technology that converts the sound of molecules smacking around into more heat which ultimately muffles the sound. I'm getting a head ache thinking about this. Either way their mufflers do nothing to help harmonics from rearing their ugly heads that I can see.