The box that Ive got is perfect for my car(a trapezoidal shaped box in the back seat of my extended cab pick-up) however, its much too large (1.2cf) for the sub Im getting (.5-.7cf recommended). Is it acceptable to cut up chunks of say...2x4, and glue(liquid nails/caulk or something) the pieces inside the box to reduce airspace? will this adversely effect the sound?
Buy two subs for your "perfect box". Problem solved and more bass. If you're a tight wad, yes any solid material can be used to reduce space this will not affect the sound.
I would cut up some wood and make the box smaller, also after i did that i would cover it with polyfill, so that way the box looks good inside and it will sound better. 1LB of polyfill for every 1 CU FT
yeah, but, behind/ underneath the polyfill is EXTRA wood so that way the box IS smaller but the polyfill makes the sound better. And all the woffer knows is how to pump out the bass.