[How to design a box?]

yes and no. if your port doesnt have enough area its like breathing through a straw and can make noise, but if theres too much area, its like breathin with your mouth wide open and doesnt build any pressure inside the box. thats where the 13-16sq.in. per cube comes in. but port length - like how far the port goes into the box - is what will most directly change your tuning. go here and play with some numbers http://www.the12volt.com/caraudio/boxcalcs.asp#porsq

[How to design a box?]

^ lol ninja'd. i completely agree with this too its honestly about the only way to do it. take notes, then test everything out.

[How to design a box?]

I generally go a little large on cubic feet, my 15 is in 6ft^3. as for tuning, usually you want something like 13-16 square inches of port per cubic foot of box volume, so my box port is 9x9=81sq. in. and 14in.x6= 84sq. in. so im pretty much right on. this lets it breathe correctly, but tuning is basically port length. the lower you want your box to sound, the longer the port. there are some great calculators on www.the12volt.com i highly reccomend and i use them all the time.

[Beefy custom 8" single 4ohm- SOLD]

^sames. I got a buddy lookin for a smaller system for a ranger. if you get anymore built im interested