at first mine was 3 cuft. then when i got a second rl-s, i put both of them in a 4 cuft sealed. so the subs were only in 2 cuft each. it got a bit louder than when it was in a bigger box. not to mention the response of the sub was better. even though mike from soundsplinter recomends bigger box, in my car it worked well in a smaller box.
