3 15's Enclosure

[Lifted2000Ford4x4]

Alright guys, moving up a lil bit on my budget build,

currently i have 2 Hifonics Brutus 15's (brz15d4) in about 6 cubes net tuned to 33.5hz,

i purchased a 3rd sub and am starting on my new box this week. so 3 15's, same woofers, on about 1000 watts rms.

I have the max dimensions of W-56.5xH-26-D-21 inches.

I want my new box tuned to 32hz.

Using torres box calculator.

what to look for? port area or port area per sq foot when tuning the port?

one person says 120 sq in for musicality. and a website port area calculator says min of 154sq in... so which to go with???

Any help is greatly appreciated.

i want to get started on it tomorrow.