40 should be okay if you dont mind dropping your low end a bit. I couldnt comment on the size though, but you might want to drop it a little bit if its going to be tuned to 40hz. My box is tuned to 48hz, its quite loud through most of the bass frequency range... but anything lower than about 40hz is out of the question. it plays them, but they just dont get loud at all.
yes... im going to build a new box, tuned to 32hz. I hope the 6db drop in average output will be worth that extra low end! //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif