WinISD has this box (32 3/8x20 3/4x13) down 3dB at 56 Hz, down 6dB at 40 Hz and down 10 dB at 33 Hz.

Is the tuning frequency always F6? I thought it was F3?

Would this larger box be less or more boomy on a suspended floor? Or would the 4Pi Pro 2.5 cu ft box be better?

Finally, I know there's a post somewhere about the size of a circular rather than a rectangular port for the 4Pi but I searched and can't find it.