im building a box for two downfiring 10" subs to go underneath my back bench. space is a huge concern (each sub needs .75ft^3 total). how much space need be made available to keep the subs from flexing into the floor? (gap between cone and floor).

Also, my amp is going to take up a lot of space (2ft x 1ft, weighs like 30-35lbs). where can i put it? right now i can only imagine putting it on the hump between the 2 subs, but it pokes out and this makes me have to build two separate sub boxes (less volume per sub)

 

Depends on the type of sub...Most likely need at least an inch between floor and sub.

You could try mounting the amps behind your rear seat for a stealthy install. Get creative.

 

Mount the amp behind the back seat it leaves room. I have 2 solo barac L7 in a downfire w/ cap and big amp behind the seats. Don't worry about airspace, you drive an ext. cab truck and dont' have **** to work with in the first place. The few inches you lose make no difference.