free air

I'm planning on putting a 8in sub in the rear deck of my sedan and it will be powered at either 200rms (4ohms) or 300rms (2ohms) from a Rockford Fosgate Prime R600-5 amp. Suggestions on good choices for a free air sub that fits this environment?

Item(s) for Sale: 1. Pioneer TS-W258F S4's BNIB Pair Free air 10's 2. Pioneer TS-W253F S4's BNIB pair of free air 10's 3. Pioneer TS-W253F S4's Used pair of free air 10's 4. Eclipse SW4010's D4's Pair of 10's 1 BNIB, 1 Tested a little 5. Infinity Kappa 100.9W SSI (Selectable 2 or 4 ohm...

So i'm building a big box to replace the 3rd row in my yukon that will hold 2 12's, amp rack for mono and 4 chan, and then also add some powered rear fill firing between captains chairs (4"s) and some rear firing 5.25 2 ways to fill mids and highs for listening out the tailgate... say when...