I see 16 holes, you said you had 6 subs right? So your planning on putting some more money into this and really going all out?
If you're really going to fill all those holes then of course fill them with all the same model speaker if possible, it will look better and sound snappier and more coherant.
I'm no expert but thats my $.02
If it was mine I wouldn't go so much for the overkill and loudness, I would just take some of what you already have and make a nice sounding ride for yourself as in loud enough for yourself and maybe a a park if you want to listen to music outside, but SQ. I think over-loudness is counter productive if you're really in to good music, doubly so if your tossing SQ out the window for SPL numbers unless you actually compete.
If you're into competition that's different. Personally I'm not into that at all although it's fun to watch the crazy vids and ingenuity.
If you want to go crazy with just the 6 subs I was thinking it might look cool to, instead of putting them flat like almost everybody does, make that top board have some 14" angled mounting headers to sort of show off the subs at like a 15 degree (or whatever you want) angle from the flat horizontal. And it doesn't matter which direction they are angled at so I'd angle them in unusual but cool looking angles that compliment each other.
In my head I see them all angled slightly outward from the center of the box. That way anyone checking out your ride can get a nice view of the nearest sub face looking right at them from any direction..
Then throw some nice jazzy fuz on that wood and some trims and your ready for the road..
I realize this is a bit more woodwork, but based on your excellent drawing, I'm sure you'd be up for it. Just a few angle cuts per sub to extend the sub up and out a bit from the wall face at a slight angle. Use some good glue and screws and it will look and sound tight!
Make it interesting and unique. You can't really stack wood on top of it anyway once your done so why not give it kind of a angled bumpy look instead of a flat sterile look.
Also you might want to think about incorporating a track on the sides so you could slide in a piece of stiff Plyboard over it when you wanted to use the rear cargo for loading up say camping supplies or w/e. You could stack a lot of stuff in the headroom without damaging the nice box. Basically a portable luggage rack inside the vehicle, and if you felted the plyboard it would look good even when in cargo mode
You could even take the track part of it out when your not using it. Just make it somehow supported and insertable into, or over, your box design.
Leave about a 4" air gap from the highest sub and that way you won't damage with sag and you could actually still use the subs with moderation. I'd mount padded spacers onto the bottom of the plyboard cargo rack underneath it so that it limited sag and rested on something other than a sub when and if it did sag.
Also you could make it so the box can easily unplug and slide out, but in practice, this isn't easy or worth it and it would be really heavy, so I like the insertable cargo rack above it idea better
Please don't flame me too much for my ideas lol, it just got me thinking and the creative juices started flowing, And he did ask for ideas! They may not be great ideas, but maybe food for thought, and maybe it will inspire something else.
Nice Truck btw.
