Of all the places to find a custom box, check out Best Buy (online only)... If nothing else you can see pictures of the boxes... That's what i did in my Sierra 2500HD crew cab... I have one 10" JL sub housed under my back seat in a custom box I built at 0.751 cubic feet...

JL Audio also makes a shallow mount sub that will compete with there "W1" models... They are pricey, but if space means more than money, they claim you won't know the difference in sound...

Email me if you want some pics of my box or if you need help with the volume/size/measurements... mazdathumps@yahoo.com

 

the thing that would probbably work best is the shallow mount subbwooffer that kenwood makes and i don't know who else makes them you could probly find out at a best buy or something and get a thin walled box also, thats what i have in my truck its a couple inches only fits really nice its a 12" sub and it sounds great. i will get you some pics of myne it works great.

 

Yeah, there are a few company's that make the shallow mount subs... I've never used them (i'm old school)... Some say they are just as good, worth trying i guess...

Also when it comes to thin walled boxes, they are fine for the average (low end) subs, but I have blown boxes apart (literally) before due to thin wood and no braces inside the box... Not fun... sometimes this will damage the speaker also (burnup voicecoil, destroy surround, etc.)... Kinda embarrasing when your competing...