I am planning a new box for a new 18" that will be receiving ~2500 watts. I have too use 3/4" mdf because that is the only way too achieve the volume that I want due too space restrictions. I would imagine that the box would flex like a mofo if I used just the mdf so I am planning too coat the inside of the box with fiberglass resin or maybe even a coat of fiberglass. Would doing so have any adverse affects on sound other than increasing spl? I also realize that this will take up volume so is there anyway too estimate how much?