[GlennH]

QUOTE: I already have the sub, an Elemental Designs 16Kv.2, in the car in a 2.5 cubic foot sealed enclosure.

Since you have it sealed and want more sound you gotta go ported. A 3-4ft cu ported box is gonna take up your entire hatch. I'd go with #2 saying that. Im not one who cares for a spare tire. Most people call tow trucks, i never see people changing their damn tires. Since you mention removing the spare, i'd go with #2 forsure. That spare depth isnt to deep so you'll have to build a false floor and raise the mounting depth. if you do go this way, have your floor a lil higher then the actual sub, so if you do need to haul something at one given point in time, you know you can lay a board over top of it without damage. maybe even plexiglass top.

if your setup is good now... why change? is it cuz you box isnt spec?