The noise from the road rushing beneath our vehicles can prove annoying. It can interfere with the quality of the sound coming from car stereo systems and make it more difficult to hear conversations among passengers. To help insulate the passenger compartment from outside noise, Dynamat sound-deadening sheets can be installed.
Park the vehicle on a level surface. Apply the parking brake and open all doors. Put on your safety glasses. Remove the vehicle's door sill plates by removing the mounting screws with your screwdriver and set them aside.
Remove the seats. Loosen the mounting bolts of the front seat with a wrench. (The mounting bolts can be located in the passenger compartment on the seat sliders or under the vehicle coming up through the floor pan and into the seat sliders.) If they are accessible under the vehicle, there is no need to raise the vehicle--they can be accessed by reaching under the vehicle approximately 6 to 8 inches. Once the bolts are removed, set the seats aside on the floor. To remove the rear seat, simply push the seat bottom down and at the same time push it toward the trunk (to the rear). When you feel it pop free of the mount, lift the seat up and out of position. Set the seat outside of the vehicle on the floor.
Remove the seat belts and carpeting. Use a wrench to loosen the mounting bolts and set the seat belts aside. Mark each belt with a piece of masking tape and a pen to ensure it goes into the correct location when reinstalled. Remove the carpeting by simply starting at the front and pulling it toward the rear. It is not glued down and will slide out. Set it aside on a clean floor.
Clean the floor of the car. Vacuum the entire floor and use a hose to wash it down. Allow it to dry completely before proceeding.
Peel the protective covering off of the back of the Dynamat to expose the adhesive and apply it to the vehicle's floor. Take care to work slowly so as to eliminate air bubbles. You can trim the Dynamat to size or cut it to shape with a pair of large tin snips. Be sure to cover the entire floor and push it down evenly to smooth it out. If you get any air bubbles, use a razor blade knife to slit the bubble and push the air out with the fiberglass installation tool. Use the razor blade knife to cut around all bolt holes in the floorboards.
Replace the carpet. Slide the carpeting into position and make sure it is straight.
Replace the seat belts into their proper position and replace the bolts. Tighten the bolts with a wrench.
Replace the seats. Replace the rear seat first by sliding it into position and push it down as you push it into place. When you feel it snap into the track, allow it to slide forward and into the locked position. Replace the front seat by setting the seat into position and replacing the mounting bolts. Tighten the bolts with a wrench.
Replace the door sill plates by setting them into position and replacing the mounting screws. Tighten the screws with a screwdriver. Close the doors.
There are some large and detailed images of this here: http://dynamat-complete-installation.blogspot.com/