vented box for Sundown V.2 18

[bosscochise 1]

I need help. I traded my 2 vvx-15 for a sundown v2 18 inch in a box that needs help. I want I box thats tuned between 30-34 htz. I want it vented not ported, I like the look better. I like how loud it gets but I would like to control it a little better when I turn it up, but I think its the box that leaks. I have a jeep grand cherokee, so I know I have the space for a large box. At the moment the the sub faces up I would like it if it fired to the back. Any help is greatly appreciated. And I am still running the planet audio bb2400.1