System overhaul, opinions on component choice/suggestions

[8ight]

Before I even begin the rest of the post, I am purchasing all NEW equipment period.

I have a budget of $1,800 for a system overhaul, and have eyed up a few components. I will be keeping several components from my current build which is in my signature.

Buying-

2x 1,000-1,200 RMS capable 15" subs (thinking Fi SSD?)

1x Crescendo BC2000D

2x 20ft 0 Gauge runs (+ and - to back)

1x New box, self built, subs up port back 6-8 cubes net (depending on the subs) @>30hz (if sub Fs allows, right?) .75" MDF (double baffle?)

1x Singer 275A alt

1x XS D3400 (under hood, single batt setup)

Keeping-

-ID CTX65CS

-SS Reference 4.400 (bridging to comps at ~150w per pair clamped)

-Head unit

-0 Gauge Big 3

Also putting my rear fill on head unit power, possibly adding new dash speakers (5x7s) to replace my blown stock ones also on deck power.

What are your thoughts, everyone?

EDIT: Was trying to avoid spamming and making lots of threads to ask about all of this stuff, so if you have input on any one thing be sure to chime in!