Looking for what to begin on a Dual DD SPL Box

[Verlaist]

Just did my first competition and won 2 first place! I am thinking I can do WAY better with a custom box. I have the Atrend DD Spec box (I know all i could get in NW Minnesota at the time). I know I can do better but don't know the first thing about boxes. Tried WIN SID i think its call but i am missing parameters for the calculator. I want to get at least 145 and maybe more after adding another M2b. Hope someone can tell me where to begin.

Thank V

Specs:

Sony XAV-64BT HU

2 DD 2512

1 DD m2b

Audio Control 3XS

Kicker 400.4

XS power 5100 in back with stock Bat in front

Mechman 240A alt

Exceleon 6.5

kicker k5 rear