2 fi ssd 15 sealed enclosure size

I want to get a a pair of Fi ssd 15's and i am building a custom sealed enclosure for them,

fi suggests between 1.5 and 2.5 cu ft per woofer, does this mean that 2 feet would be the ideal? this is my first time designing my own encosure and i would like to have the optimum internal space.

would a 2.5 ft^3 make them hit any deeper or will they sound better with 2ft^3

(these volumes are AFTER displacement of course)

i am really going for a sq build here

please do not try to talk me up to the Q,, i am sticking with ssd's with the bp power upgrade the standard coils

that being said i would love to be able to hit the low note in "put on" with this setup

i am not incredibly worried about a huge spl number as long as it rattles my brain a bit

win-isd confirms the bigger box theory but i wanted a little

human input as well

more details about my system if it would help

wiring is more then capable, 2 powerbastard HO alternators (~250a each at 2k rpm)

1/0 gauge wiring of course for big 3

3 total xs power batteries

dynamat trunk and ceiling

(overkill for this system but i have bigger plans for the car in the future in the future and they actually only put out about 110 amps at idle so 2 gives me really steady power)

plenty of amp power for them

each will get its own rockford fosgate t1500-bd running 2 ohm ( both birthed 1350+@2 ohms)

(if that isn't enough power i can drop to 1 0hm by piggybacking the amps)

i listen to all types of music, a lot of rap, but also metal rock and techno