Here's a write up on how I built a fiberglass box for two Image Dynamics ID8v3's in the spare tire well for a 2000 Civic Si.

The challenge was to get some sub-bass in the car without losing ANY trunk space, and without sacrificing the spare tire.

Depth and box volume were the two most difficult challenges. After some measuring, I found 0.7 cubic feet between the spare tire and the rear of the car. The jack was relocated to inside the spare tire itself.

Here's what I had to start with:

The first thing I did was use masking tape to both form the mold and to protect the car. Always mask more then you think you will need - fiberglassing is very messy!!

The tape was then sprayed with a few layers of PVA to act as a release agent:

Next, I prepared both fiberglass cloth and knytex - a cloth/matt hybrid - it's my favorite material for glassing:

Add some resin, 3 layers of glass, a few disposable paint brushes and a little MDF to shape up the notch around the brace for the jack and you get this:

The box was notched to allow it to be easily removed. The next step was to remove the mold after it had plenty of time to cure. The mold was then trimmed up, and a piece of 1/2" mdf was cut to act as a mounting flange for the baffle. The flange was attached to the box with fiberglass reinforced filler (Dynaglas). You can also see the underside of the MDF baffle that was created from two pieces of 1/2 MDF:

With the baffle glued, screwed, and caulked, approximately 80% or more of the baffle was 1" thick - solid as a rock!

Here is one woofer test fitted into the box. You can also see the trim ring that I routed out to cover all of the mounting hardware. You can also see the stepped design of the baffle that allows it to fit under the factory trim:

Some carpet later:

The box was coated in a milkshake before the subs were added. This was a mixture of resin and cab-o-sil filler. It sealed the box against any possible airleaks.

The trim rings were chamfered on the inside diameter to give them a nice touch, were sealed, then sprayed gloss black:

Here's the box in its new home:

The box fits perfectly under the factory floor. The subs were recessed to allow plenty of room so that the surround will not rub during use.

This design not only maintains 100% of the utility of the trunk, but it also maintains the spare tire well.

Because the well is off-center, I built the box so that the subs would be centered on the trunk. This would allow Eric (the end user) to customize his trunk with a false floor if he wanted without having to rebuild the box. Had I centered the subs on the well, he wouldn't have this option.

How does it sound? Well, with 300w of power, I must say that this little box was very impressive!

Since most people are interested, total weight was around 35 lbs.