I have to agree with Loyd. You need to find the happy medium between too large of a box and the power that you want to put into it. I talked with a ED tech about putting 3 12" K's (in place of my HE2's) in a 6cu' box. He said that it would work out fine, but then again I was only going to put 300w rms to each of them. If I wanted to go with more power then i would need a smaller box to provide the adequate back pressure to compensate for the power increase.
I by far am a the box master but I hope this helps...at least a little.
2006 Jeep Liberty
Adire Audio 15" Brahma running off Cadence A7hc, Clarion hu, MB Quart 6.5s and 5.25s running off old school Punch 800a4
146+db @ 38hz with 1200w and a single 15"
Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
*Vb = vol. in cu"
**R = sq.rt. A / Pi (for square/slot port)