Then the wood would just move around..which defeats the purpose.i've always put a piece of wood under the carpet and just mounted the amp to that-if you do drill through the floor, make sure you don't hit anything "vital" such as gas tanks, etc
but the screw will be touching the amp and the cars metal, rightWell there is carpet between it..
dont do amp straight to the floor..i was stupid and drilled into my gas tank ... a few times before i noticed
i would do a thin layer of wood between the carpet and short screws... the carpet will hold it in place and the wood will hold it down...
should be quite stable.