I've finally decided to just build a wall in the back seat. Got tired of building in the trunk. This will be my first attempt at it. Only concern is where is the strongest place to bolt the enclosure to the car. And what kind of bolts to use.

be careful the gas tank is right underneath the rear seat so if you are bolting it that way be careful you will want to drop the tank. I screwed mine in through the hump that goes where the seat back would go and it has held fine. I dont remember how many or how long its been awhile. also made some support braces that hold it into trunk

my thoughts and exp. is to build a level sturdy frame on the "floor" where the bottom seat cushion used to be. use 2x4 and frame it in. then u can use ur seat belt bolt holes fab up a metal bracket out of 3/8 or thicker steel, not alum. if u frame in and out of the drops, on each side of ur box u can run a 2x4 to ur trunk and just screw the box to the frame.

Thanks for the info guys. Dustin i think i'll go with your suggestion of using the seat belt holes.

Another thing that i was thinking about last night was what will happen with the suspention and the weight. I have stock suspention and never really planned on up grading it. Would i have to upgrade in order ot handle the added weight. chances are i will build the box partialy into the trunk and using as much space in the cabin as possible. i'm guessing with everything finished I will be adding around 500-600 lbs. for the box, subs, bracing and stuff. And come to think of it will the brakes need upgrading too?

my wall is an inch thick all the way around and roughly 13 cubes external. the subs weigh about 50-60 pounds. optima in the trunk and about a half sheet of 3/4 mdf in the trunk. plus the 2500d and 750x/ I dont get much of a squat. not noticeable really unless you are looking for it./