Says who? I've yet to see any real scientific testing done that I would consider effective. Which would of course mean, doing decibel tests in several of the exact same, new (or newer) vehicles. I realize of course, that thicker aluminum is of course going to yield better results. But there are several brands with comparably thick aluminum and like everything else, there is going to be a point of diminishing returns. Past that, you're just paying for nothing. So while I have nothing against Alpha Damp, I'd still like to see some proof to everyone's claims. Everywhere I go someone is shouting from the rooftops that its the best of the best, with little actual evidence.
There have to be other brands that at least get very close. I have my doubts that its by far the best and no one even comes close.