okay so I have 2 mtx 10" 8ohm 500 watt subs.

Sealed inclosures recommended: .75 ft^3 for each sub
Vented Enclosures recommended: 1.5ft^3 for each sub
(with a 3x12" openeing on the vented for each sub)

Sealed will give 111dB's at 250watts.
Vented will give 113dB's at 250watts.

now remember, 3dB's higher is twice as loud.(I think thats how it goes)

However it's also possible to do 1.0ft^3 for each sub on a vented box. Only thing is, it probably will not be as deep of a bass.

So tipically people have been Rasing the seats and removing the centre brace.
Okay thats good, but how about removing all the braces?
Imagine how much more room that would give you, and as long as you make your box STURDY and secured to the foor, it should be all good.

Well, whatever I do I'll be sure to post alot of pictures.

Peace out, Craig