It'll be loud no doubt any way you go. If you want that bass snappy for all types of music, 12s would be the largest I would go.
Maybe look at 8 12s sealed?
If you watch your voltage there's no problem running off a bank. I've ran my 11k .5 load on stock alt and a bank for over a year with no big 3.
After your amp draw exceeds your alt your you'll be on bank power. It just took longer for my bank to charge up.
Just know your limit and things run charry
heres the link to my build:
http://www.stevemeadedesigns.com/board/topic/112752-dc-vs-sequoia-build/page__p__1576705__fromsearch__1#entry1576705
ill have my plates in this weekend.
Without bracing the outer port wall will flap.
With having the port that skinny and tall it was noticeable that the air was stronger at the top and bottom. When i dropped a board down the middle it evened out the air flow and I did gain .2. And that was after I used rods for bracing.
That setup I was doing sub up port up below the line. I'm now doing a wall.
Drop a brace all the way down the middle of the port to brace and even out the air flow.
I just built a box like that and if you leave that port open like that it'll flap like crazy.
you have to know what your looking for. gap size, former length is something so small but makes the sub. most other parts are similar. if you need it stiffer add a spider.
what differences are you looking for?