I went back and forth on what type of insulation to use for my interior. My car originally came with the factory tar sound barrier, but I was hesitant to buy a repro kit. Plus its so freakin messy to work with. Not to mention, the heat insulation qualities aren't that great either. So after a bit of research I decided to go with Flatline. You can buy the cheaper generic brands in non-cut sheets for less money, but I thought this was a great compromise between the expensive dynamat stuff and also having to trim everything to make it fit.
It's super light weight, probably weighing only a few pounds for the entire kit. The foam thickness is about 1/4 inch, so its pretty substantial.
This stuff went in very easy. The backing peeled off without a lot of hassle. You could work with it as long as you didn't push it down hard in place. I did try to remove one panel after installation and it started to tear the foam backing so I just lived with my initial placement.
The kit should have come with a little more detailed directions, especially for the front floor panel placement. I dry placed everything to where it made sense and couldn't get the front to really line up as well as I would have liked. So I just took my best guess at it.
Trimming was minimal and pretty much just around the floor shifter cutout, and hardware mounting points. It's already precut for the seat mounting points for both the front and back.
It sticks well once you press it down. A roller would be helpful, but isn't necessary.
The other issue I had with it is it has some sort of nylon woven thread that holds the reflective material to the rubber backing. This tended to break and come off as sort of shedding when pressing the material down in the corners. It didn't compromise the integrity of the material, but the fine threads were annoying to remove.
Here are some pics of the kit and the install. Retail price is around $350 for a complete floor, door and roof pre-cut f-body kit.
Kit

Dryfit

Backside

Installed

Also, here's a link to a video about the product.
https://www.youtube.com/watch?v=N54ttGCMlQ0