I just measured my box out and I ended up building mine at approximately .02 ft3 smaller... I think this was an accident. As you can see I made them slightly narrower but I made them deeper to make up the volume... I think I must have fudged it a little when I started assembling them.
Either way, fixing the port length and swapping the stuffing made a HUGE difference.
Quick question... I'd like to make a larger box for my next pair but don't wanna go a big as the tower... would their be a benefit to say going with a 2 to 3 ft3 box? I assume for port length I would just calculate for a 40hz port?