From: bjfish11 - enclosure material question

Ok, I couldnt find the displacements after a real quick search of the drivers. I went with .1 per.

So a .8 cube gross box built with my regular 3/4" Trupan would weigh in right at 13 lbs (not including screws, glue, terminal, carpet, etc.). A box with the same internal air space but built out of the 5/8" Trupan light would weigh in at 9.165 lbs. By the time you throw in some added bracing, you would be in the are of 9.5 lbs.

Overall, the weight you would save, would be not be noticeable. Since we are talking ~3.5 lbs, I would probably recommend just going with the 3/4" material. But thats your call.

That's very helpful and educational.

You see, the horizontal section of the trunk cage is slightly more than 7.75" above the floor. As I would prefer a downfiring enclosure - mostly due to aesthetics - 3/4" doesn't leave me much room to work with. The drivers are 4.5" deep. As far as audio, I'd much rather go for 3/4" with a double baffle and structural reinforcement, and I will do just that for another project. In this case, the car is the focus; the system is secondary in importance, so I'll most likely opt for 5/8. That'll leave me ~1.5", or just a little more, between the floor and the box. As you mentioned, the ~4lb difference in material isn't enough to lose sleep over.

Thank you taking the time to look into this.