Nissan 370Z Forum - Behind Seat Sub-woofers - Custom Fiberglass Enclosures

I recently traded in my 370Z and in selling a few things realized that I never posted a build thread for my sub-woofer enclosures. When I was upgrading the audio system I decided that I didn't want a massive sub-woofer and didn't want to take up any room in the trunk. The core of the system was an Alpine Navigation Head Unit and an Alpine Amplifier that I mounted on a small shelf in the space in the trunk just behind the roll bar. I originally wanted to fit the sub-woofers in that space as well but didn't have the necessary volume.

I replaced the speakers in the doors and dash with JL Audio and also added rears. To round out the sound I decided to try a couple of JL 6W3V3-4 sub-woofers. Since they're only 6.5" I also decided to port them. I spent a good amount of time looking at volumes and locations for the subs as well as how permanent I wanted the installation. That's when I decided on removable, ported pod like enclosures and went with the rear shelf location.

The enclosures we designed to rest snugly in the rear shelf spaces without the carpeted insert in place. The base, back, and speaker ring were made out of MDF then the sides and top built up in fiberglass. I laid fiberglass to about 3/8" thick then smoothed the surface with resin and Bondo before priming and painting them a flat black. The bottom and sides are lined with felt and the face sprayed with Plasti-Dip for a rubberized, textured finish. I thought about going with vinyl or just leaving the painted finish but I wanted the texture to match the interior and the surfaces were too complex for my vinyl skills.

The final product ended up matching the look of the interior fairly well. Once powered up, the sound was better than I'd expected. The tone was very deep for such small sub-woofers and there were no issues with the ports or the sound being off due to their angle. I did, however, do my homework along the way and ensured the cross section and center line length of the port was to JL specification and actually made the internal volume of the enclosure to specification as well. Given the geometry complexity, I used a known volume of sand to figure it out.

Attached are some pictures of the final products and the build. Hope you guys enjoy and get inspired to build your own.