hey i'm here
it's not so much the dynamat itself, it's the physics behind it.
what happens is when you apply dynamat you are actually changing the resonant frequency of the metal it's attatched to, creating a more dense panel which will vibrate at a much lower frequency eliminating the tinny rattles. it must be applied thouroughly though, you need to clean the surface smooth and make sure it sticks and conforms to the panel everywhere it touches it. if it does not it will not change the resonating frequncy as effectivly.
i've used dynamat original and some other off-brands that were half the money with the same results, how good it's going to work all comes down to the installation.