Boston makes a fully assembled box with either one or two 10" Competitor subs, each with a passive radiator on the back side (a flat woofer with no motor structure). The boxes are TINY... the single sub box is roughly 12" wide, 10" deep and 12" tall... and the double box only being about 25" wide. These things really POUND and play LOUD, while staying tight and clean.

Model #'s C110 or C210

They also have pre-fabbed boxes containing Generator series subs... which also sound AMAZING.

I suggest these boxes because of the incredible box construction... they are built like a tank!