well i just found out the cubic feet of the box and it is 0.8 which is the min for the kicker comp vr 10's. so it could sound good
hopefully. There is a lot more to box design than just slapping it together in a form that fits a space. Obviously you have the bear bones basic stuff like volume and port dimensions (on vented or bandpass), but on sealed boxes you still should account for standing wavelengths, and when it fires down like you have it essentially becomes bandpass which brings in acoustic coupling/acoustic cancellation and you get the flexability to tune it a little bit by adjusting the dimensions of that vent. You can also taylor it to the vehicle by taking some internal measurments to the windshield and to the listeners ear and measure for a 1/4 wavelength of the desired tuning frequency so that you can get the most output.
the sub is probably the least important part of the equation. You can make inexpensive subs sound awesome with a well thought out design and good clean power, and even the nicest sub in the world will sound like **** if you don't take the time to build a box to maximize it's specific characteristics and then even taylor it into the internal dimensions of the vehicle it's going in.
That all being said, in highly space limited situations like you have under a truck seat, it's becomes increasingly difficult to account for all of that stuff. and just getting a box to fit is an accomplishment of it's own---so good job. I had two 10's under the back seat of my dodge in a thermoformed box and it sounded good enough for me. If I were to go back I probably would have run a single 10 and created a vented box under the seat to use all of the available volume. That would have been louder and cleaner than the two 10's wedged into a box that wasn't made specifically for them.
I really miss the stereo in my dodge.
