smart boy , whats the defect on 4" port mouth ,although its seem weird , but tunning frequency touches 36+
and at 3.5 , it gives 30~34hz etc
Length = 30"
depth = 20 "
height = 15"
L = 4"
l port length = 6~8"
you check it out on re - enclosure calculator
MTX , bahi you will need 2000Wrms amp + alteast 5 cuft box , min 4.5
cause fi btl is spl based subwoofer , and support lows like earth quake
20~25k sae uper ka hoga , if you know importing issue , i can let you contact with my friend , but duty tax , other tax will hit almost 50% ( i think , you better know )