Another question,

Running into problems designing a box that will fit within the space I have, allow the actual mounting of the sub, and getting the required volume. I'm using an existing sealed storage compartment as my sub box. The opening is smaller than the inside of the compartment. I will not modify the compartment in any way, in case I want to reinstall the door and use as a storage compartment. Ay box I make will have to fit thru the existing opening, which is creating a challenge. OR I can place some solid material in the bottom of that compartment to take some volume.

Can the volume of a box be decreased by simply placing some solid material such as wood to take up some of the volume even though this 'filler block' won't be sealed along the edges , for lack of better description, scraps just tossed in as fill but secured to prevent moving around.

Fill in the area with spray foam insulation from home depot etc. that will absord the extra air space.

That won't work, to easy of a solution. :)

Thanks