FWIW - Peel n Seal does a fine job. That is, it quickly and easily adds mass to otherwise light and vibration-prone metal panels. I've done several installations with this stuff, and it sticks very well. In fact, it can be very difficult to remove. Installation is all in the prep work. If you have a clean and dry surface, and take your time pressing the PnS on the surface, it'll stay put.
I'm currently working on deadening my front doors, so I'll put up some photos soon. I'll be adding RAAMat ensolite foam as well.