If it can't be measured and it's effects can't be reliably identified under bias controlled blind listening conditions, what is it's relevance in the real world? I for one would never waste a penny on any device that couldn't meet those standards.
If you came to me with a performance enhancing product with claims of increased power, I would put the vehicle on a rear wheel dyno and maybe run it at the dragstrip. If the numbers didn't match the claims you would be laughed out of any serious discussions.
Cars with louder exhausts can sound and feel faster too. But many times the numbers prove a loss in actual performance, but the driver loves the way it sounds and has no real interest in the numbers. He doesn't even want to see them. Sounds very familiar to me.