JBL 12 inch vs RE SX 15 inch, help

[Paul Kadoshnikov]

Alright here is the key:

The Blue line represents my current JBL setup 33 hz

The Green line represents my theoretical Re sx setup 33 hz

The Orange line represents my Theoretical Re sx setup at 25 hz

The Purple line represents my theoretical JBl setup at 25 hz

as you can see the 12 inch JBL is much louder than the 15, but i am confused by the difference between spl and the amount of air it moves, would the jbl be the better choice for the 4 ft cu box or the RE SX 15 inch, the 15 inch in the box doesnt get any gains and still shows up quieter than the JBL, is the program just wack? And in other threads ppl have claimed to achieve rather high spl with 1 RE SX, but the program shows the max to be less than 130 even if the box was 8 cu ft. so does this mean the JBL would be better in the 4 foot box in all conditions?