sweet thanks for the answers so far, well for my box rite now its looking like 5.5 cubes net, common chamber, 45 degree angles in all corners, maybe even fiberglass the inside, with two external 6" aeroports 6.5" long, this is for 2 L715's in a 2000 mercury cougar, my current box which is daily, 4 cubes each, seperate chamber with 3 4 inch aero and i forget how long i made them lol