fischy fisch

hope i writing this in the right place but i need help with the enclosure i built the original box from the spects the dude gave me @ spl (the subs are splw 12in ) his box size was 2 cu. with a port 25sq. in x 13.5 it was an ok box for a little till it broke it was doing 135.1 @49hz can anyone help me with the new box need spects and would like it to be ported at 40hz just need to be able to bass race in the 139.9 class