I'll take some pics tomorrow when I'm working on it, but here is the rundown:

Fi SP4-18 D1
Audiopipe 3000D
2006 Mustang GT Backseat Removal
75 AH Batt under seat
Stock alt (we will see, not gonna push more than 2k watts)
CDT Three Way Comp Setup /w Kickpods
M6's in Doors
M4 / Super tweets in kicks off of a Soundstream 250x2 Amp

Shooting for 6 cubes @ 30 or 32 hz.

Building this box in the backseat is a real PITA but its coming along. Hopefully my sub ships before the end of the week.

post pics soon.

Two pics, box is coming along!!

Nice so this isnt a wall?, I have built a couple boxes for sp4's and heard lots of cars with them. I would recommend building in 7-8 cubes. These woofers are the most volume hungry subs around and need tons of space for lots of output. They are beasts as long as you give them the space they need. If your removing the seats may as well wall 2 18s when you get the funds imo

Also if that is a 4.6L pcm regulated stang i have a 300 amp excessive amperage alt which would be direct bolt on from my crownvic

Yeah I'm a little short on space, I'm invert mounting it and I wanted to keep my rear window open pretty well, so we will see how it sounds in 5.638 cuft. If it fails me hard (which i dunno, i mean i've WinISD'd the thing and it looks decent for 5.6) I can actually cut a hole on the back and put an extension into the truck a bit and pickup another 2 cubes.
How olds the alt and what would u want for it?

http://www.youtube.com/watch?v=jpzOaqJWDA0

shitty rattle noise is from a panel in my interior rattling lol

wuts that song? i heard it somewhere ........