help for box build RE AUDIO XXX 12'

[ninos306]

building a box for a homie for a single 12' re xxx. its going in the back of a jeep grand cherokee, hell be running about 1500watts to it. wants it tuned 32hz ish.

this is what RE says :

1.7 cubes at 35hz

2.2 cubes at 34hz

so i was thinking about 3.2 cubes at around 32. using aero ports? what do you guys recomend?

port up, sub back? some help would be nice!