Audio guys come in. Need some minor sound proofing

Since removing the OEM carpet and going with BedRug, I have lose some deeper base from my Alpine sub under the seat. There is no insulation and I can tell the bear metal has taken some sound/depth away.

I bought some insulated heat shield to glue under the carpet to see if it helps, or wondering should I lay so dynamat instead. or make this: Noico RED 150 mil 36 sqft Сar Sound Insulation, Self-Adhesive Closed Cell Deadening Material (PE Foam Sound Deadener)