I have two subwoofers, 2 12in DHD's 2000 watts each, i have them in a pretty small box for 12inchers, its roughly 3ft lenght,2ft width, and about 1.5 ft height, its enclose but on the sides it has two openings to let the air out, the bass in my car is good, the rearview mirror shakes like crazy, so do the side view mirrors, u can feal the doors shake, the whole hatch with the spoiler shake like crazy, the seats shake and you can feel the bass pretty much it makes your whole body shake LOL, there pretty loud given the fact im only supplying 800 watts of total power to the 4000 watts it can hold
From what i know mostly from the guys at the stereo shop they told me with plexi glass the bass notes hit harder, than the regular boxes. I can say i agree with them cuz they had display boxes that both had a regular box with a 12in, and a plexi glass box with a 12in, and by comparing both i noticed that with plexi glass it hit harder than a regular box well thats just my opinion, i would of gotten a plexe glass box but it has 100 bucks for it instead of the 35 i spent with my current box