It is my great pleasure to introduce to you...

...my new stereo install . Since 1CLNB14 called my old setup "ghetto" (which it was...) and the box was absolutely massive and took up half my trunk (1.25 cubic feet for a 10"... what was I thinking?), I decided to re-do it about a week ago, with four goals in mind.

1. The box had to put audio quality first. I designed parameters for the box dimensions and built the rest of the system around the sub box.
2. The box had to look relatively factory. Going with my goal with the Sentra to be my interpretation of what the stock Sentra should have been, the box had to blend in well with the factory decor. This meant no crazy fiberglass, no weird colors, and no Plexiglas windows, etc.
3. The box had to take up a minimum of space. My car is a daily driver and needs its trunk. Floor-mounted subs and amps are a no-no.
4. The box had to leave the spare tire in place and fully accessible without removing the box. Since my car sees around 200+ miles of freeway driving a week, the spare tire was a must.

With these goals in mind, I designed the box. I settled on an interior volume of .72 cubic feet, including the displacement of the sub. Unfortunately, this was a little small for the sub (recommended volume is .80 cubic feet, not a huge difference), so I decided to use the 1.5 lbs of Polyfil from my old box in the new one. I decided on .75" MDF from the local hardware store, which cost me $23.35 for a 4x8 sheet, plenty for what I was doing. Unfortunately, my first bit of cutting didn't turn out so well. The angle markings on the saw were not very accurate, and my beautiful 45-degree miter joints turned out to be 50-degree, enough that all the panels had to be scrapped, along with the idea of using miter joints. I recut the panels and attached the new ones using a thick layer of Elmer's white glue and 2"x8 self-tapping flat-head screws, countersunk into the wood. Once all six panels were in place, I layered on an 1/8"-thick layer of Bondo on the inside to seal the box. This ultra-messy stuff has a horrid smell, and I highly recommend good ventilation when working with it. I'm sure I'm about 500 brain-cells short now.
The amp mount was a little trickier. I wanted to be able to see the amp and I wanted plenty of air to get to the amp, so hiding it was out of the question. However, going with the stock look, I didn't want to be able to see the mounting screws or any wires. Mounting it through a cutout from the back seemed like an interesting option. I cut a panel that extended off the side of the box and cut a hole for the amp to mount through. I also chiseled away the back side of this panel to provide room for the wires. The amp was mounted through this panel so the heatsink faced the same direction as the sub and all the wires, controls, and mounting screws were completely hidden behind the panel.
To make the box and amp mount look a little more factory, I make a panel to mount on the top that fit the contour of the wheelwell and all the junk in the trunk of the car. Using a piece of aluminum foil and a piece of cardboard, I made a template and cut it out, filing it down to fit. This was mounted to the top of the box with 1.5"x8 screws, countersunk of course.
The floor of the trunk also had to be redone, since the old floor was a cheap piece of chipboard that was sagging from two years of various heavy guitar junk in the back. Using the same MDF, I cut out a new three-piece trunk floor, one piece for the back of the trunk, one for the right side under the box, and one for over the spare tire. These panels were connected to each other using short wooden dowels that are drilled into one panel, and a cut-out to fit the dowel in the corresponding panel. This keeps the trunk floor totally flush and is strong enough to support upwards of 100lbs in the trunk. Any more than that will require removal of the floor, which is amazingly easy thanks to this dowel-system.
Keeping with the stock look, I chose a dark grey fleece as the material for the trunk floor. This fleece is very stretchy, making it easy to carpet, very soft, and is a beautiful charcoal grey color. It's also surprisingly strong and very difficult to cut with an Exacto knife . Using Elmer's Spray Adhesive, I attached to to the faces and exposed sides of all the panels. The bottom of each panel is uncarpeted since you can't see it and to save material. I also chose to carpet the sides of the trunk to match. This material proved very easy to work with and made beautifuly smooth creases on every panel.
The sub was installed using 1.5"x8 screws and the box was filled with 1.5lbs of Polyfil to help make up a little for the small volume. Wiring is done through a sealed terminal cup.
The sub is a Panasonic EAK-WG25. It's a 10" sub designed for 120w RMS and 450w peak, with a sensitivity of 90dB/W/m and a 44.9 oz magnet. The amplifier is a Kenwood KAC-428S that puts out 100w RMS and 200w peak in bridged mode. Wiring is using Monster Cable 4-gauge power and ground wire and Monster Cable C-5M RCAs. The sub recieves power through 16-gauge standard speaker wire.
Some final adjustments still have to be made to certain panels to make the fleece hold a little better, but this is what the finished product looks like. What do you think?