Diamond Audio TDX 12D4 Sealed Enclosure

I'm trying to design an enclosure for the Diamond Audio TDX 12D4.  I'm thinking sealed, but I'm not 100%.  I hate how ported enclosures always seem to have this peak frequency where they are way louder, I don't like the way it sounds.  But they are so much louder.  So I will ask a few things:

Does anyone know what the sealed volume should be for this sub?

Can Anyone attest to the SQ differences between sealed and ported with this sub?  And can you get a ported enclosure with a more mellow frequency curve, with less peak.

Is VB ft^3 a representation of enclosure volume? 

Whats a good shape for this box?  I was thinking a wide rectangle with the sub mounted at one end of it, and with the rear of the enclosure slanted. 

I want this sub to pound, but SQ is more important to me.  I would also like to get a

Sorry, didn't mean to spam

1 sub, and it will be pulling 1000 watts rms at 2 ohms from an alpine m1000.  It's going into a 97 civic 4 door sedan.  Probably firing forward, with seats folded down pretty much always.  What kind of sq differences will i notice between a .55 and a 2.5 cubic ft. box?

Also why do you say just build a rectangular box?  I will have no problem constructing solid box with angles, let me worry about that, I'm wondering what box shape will give me the best performance. 

You never want a flat wall behind your sub in a sealed box because it produces standing waves which arent good for sound quality. Also Bigger doesnt mean more, it means deeper. I would recomend building a box about 2 cubic feet and build it with that slant in the back, it doesnt have to be insane, just so long as its not strait. If you have the time and money, nothings better than trial and error. Build a couple boxes of different sizes then pick the one that sounds the best. If you are building your own than this shouldnt be much of a problem since a sheet of MDF is like 25 bucks. Build a box then try it for a couple days then try the next one. This is what I did in my car and it took me 6 boxes to get the desired sound and they were all 6 cubic feet and larger. On that note does anyone need a coffee table :)