That looks like an awfully small box. How does it sound? Any rattling from the spare and jack? I was thinking of doing the same thing but actually remove the spare tire and fiberglassing the entire trunk well.
The sub is made to work in a small box. The only rattle is from the.exhuast sheild under the car where the spare tire is. Sound is awesome. I had some body built the box for me. I but the Jack in one of the side cover where u can pull up