I need some help. i have two 500 watt 15" Audiobahn and i want to put them in to my Astro Van. the only thing keeping me from putting them is that i dont have a box or messurements to build the box and i dunno much about what size box will sound nice in my van. and i whant to ask people that are familiar with these things so if i can get some help in any way i will appreciate it.