I'm about 1/3 through soundproofing my rig with their products, and just wanted to give them a positive nod here on the forums.
You get a great product that works at a competitive price. The materials work very well, too.
I've got my entire floorpan and firewall covered in their Spectrum and Damplifier Pro. Both products mean business. After these successes, I've now got plans to hit the A and B pillars, roof, doors, and back firewall with the regular Damplifier in the near future. This stuff is very different than the tar-based peel and seal and has gone a long way to working the tinniness out of my pickup.
Worth the time and money.

 

As an update, I've finished with the cab of my truck.
I haven't driven it yet, so I can't say how effective the project has been for engine and road noise, but this thing is like a tomb right now.
I've run their full product gamut over just about every inch I could, and the floor pan and firewall sound like I'm knocking on solid birch, almost no sounds transfer across it, even in the mildly covered areas.
The doors, these things have 3 thick layers of Spectrum, damplifier on the inner faces and Damplifier pro on the back sides of the front panels, and closing these things is like slamming the doors on a walk-in freezer. It's amazing how these products have worked out.
In a week or so, I'm hoping to get some ABS sheeting to make into inner panels to "dress" these doors. These panels will also get the Second Skin treatment on the inside to effectively turn the voids of the doors into baffles to reduce sound transfer.

 

Got any pictures to post?