No, there is no reason to glue anything. I've never used any sound barrier before, but I've seen guys install it and it looks shinny side up. It seems to be heavy enough to sit in place.
No glue on the carpet in case you need to lift it some day. Start on the centre hump and work out, use the palm of your hand or a rubber mallet. Form the carpet down to all the contours of the floor. Leave the seat belt bolts, seat bolts in the floor and cut a X across them so you don't have to find the holes after. When you go to cut off the extra carpet at, kick panels, rear seat, sill plates, under the dash, leave lots. You don't want to cut short and have it show.
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.
When you are installing the carpet the trick is to use a heat gun to mold the carpet to the contour of the floor. Heat it from the top, not the bottom. Don't overheat the area or the plastic backing will melt or the carpet fiber will melt. The backing will stretch so make sure you don't concentrate on one small area or you may see a gap in the carpet fibers.
Like bowtiedown says "start from the center hump". Don't cut out any holes until you have the carpet formed how you want it. One you have the carpet laying down the way you want start opening the holes, again from the center and install the bolts/nuts with washers to hold the carpet in place. Cut the length at the kickpanels, rear seat and door openings after everything else is done. You may have to trim small pieces off as you are going to get it to lay down especially at the kickpanels. Don't get in a rush. The first one I did took about 4 hours. You'll be surprised at how well it can fit.
