Here is what I did....and pretty low budget. The pictures show the back seat of a 2003 F350.....about the same. Cant see any of that with the seat back in.
Kenwood KDC-x996 (amazing head unit) - $200
Polk MOMO Carbon Series 300.2 - $50
Polk MOMO Carbon Series 400.4 - $40
Alpine MRP M500 - $100
2 12" Kicker CVT's 4ohm (wired to 2ohm)- $150
Infinity Kappa 682.9 (front doors) - $60
Infinity Kappa 42.9 (rear pillars) - $50
About $650 total.
Alpine Mono amp was open box....never used.
Kicker CVT's were pawn shop....perfect condition and work well. I used polyfill in the box (1# per sub) and wired them down to 2 ohms.....500 watts from the amp split between the two subs is still enough to vibrate my rear view off. They have loosened up and get better as time goes on. I did not know that would happen.
Polk amps....one pawn shop and one CL. They both work well. Nice and clean in and out. I like the way they look side by side. I couldn't pass up the second one I bought, even though I really didn't need it.....have room for growth, I guess.
The 6x8 Infinity speakers were bought new.....if I had it to do over, I would have gone with components. But, these are good.
The 4" Infinities give a good, high rear fill. Bought them off another forum and still have one pair left.
The Kenwood is excellent....everything you could want in a head unit. Sounds excellent and the features are great, adjustments for everything to customize the sound to suit the individual.
I am very happy with this set up....especially for the price. I walked in to some good deals for good used (and new in box) parts.
I moved the seat forward 1 1/2 inches (drill holes) and took those rear vents out and sealed it up real well and used some sound damping (not the high dollar stuff). I actually found that the anti fatigue mats used to stand on in the garage (closed cell foam) helped greatly. I glued it on the back wall and used under the carpet. I could hear the difference before I put it all back together.
Everything hides away nicely under the back seat (and behind it). I did not want a big advertisement for the thieves.