On this particular aftermarket carpet in the Scrambler, no padding underneath the seat risers. The padding is only on the very front portions, driver and passenger foot wells and the transmission hump, just where the shifters are. No padding further back.
Bolting the seats down on top would be fine. The only concern with bolting the shifter boots on top of the carpet is that mud/water/cleaning the engine gunk always comes up between the transmission tunnel cover and the shifter boots. The insulation would be between the shifter boots and transmission tunnel cover and would get wet, mold, and stink. Keeping the tunnel/shifter boots sealed keeps the carpet insulation from getting funky.
The OEM carpet in my red Scrambler has NO padding anywhere, just thin carpet on the backing material. Even this thin layer is great at sound/heat absorption. I imagine the padding added to this after market carpet will be great in this regard.
My red Scrambler leads a much more interesting life then my green Scrambler. The ease of removing the OEM carpet for cleaning/drying out has spoiled me. My red Scrambler gets wheeled, full of mud/sand/water/rain, so quick easy removal of carpet makes sense.
In my green Scrambler, bolting the interior down on top of the carpet would have been OK. In reality, if the carpet gets wet, you could pull up the foot wells and rear, pin them up, let it dry out. These areas get wet the most, not the center.
The OEM carpet is a courser grade of material, and it dries out fast. I hose/pressure wash it sometimes in the summer if it gets real dirty. It will completely dry out overnight, if left hanging. But, it gets hot down here in the summer.
This aftermarket carpet is "nicer/plusher/softer", so probably not as durable/quickly drying as the OEM carpet, if you wheel a bunch. For my green Scrambler and how it is used, it will be fine. But, I just wanted the ability to remove the carpet fast, if need be.
Long winded response LOL. I will say one thing, for my uses, I would prefer the OEM carpet. It is just hard to find in good shape, correct transmission cut out, etc. It costs more, but I spent 8 hours cutting up this aftermarket carpet, and still not finished!!! So, a time saver, too.
I do like this ACC carpet, seems nice, fit great. Not the easiest thing to start cutting up brand new carpet, but I really wanted to replicate the OEM design. I will have to fit and finish it, see how it works out