well dd recommends a 2.5 ported box tuned to 45 for their 9512 subwoofer
i've emailed them and told them i'm not going for spl but sq and they said that when put in the car...it is actually lower than 45..never got it but they said just built it to that spec and lengthen the port to 18 inches instead of 13 or whatever it is on their website...
never got the chance to build the box for it yet, but will this summer
and i'll post up on sq...right now its in a 3cu sealed...yea yeah, but with what i had to work with at the time...can't do ported
it sounds pretty good not great, but alright...
i'm sure they sound pretty good put into the box that THEY have up on their site