Well, some kids wonder "ZOMG, WHAT BOX SHULD I USE?!?!?! IZ PORTED TEH BEST?!"
Well, I used WinISD Alpha, I used a pair of Audiopipe TXX-15 drivers, with default specs.
Here are said specs:
Ported (AKA Vented):
tuned to 22.97 Hz
4th order Bandpass:
Rear chamber: 6.987 cuft
Front chamber: 4.179 cuft tned to 40.99 hz
6th order Bandpass:
Rear Chamber: 3.531 cuFt tuned to 20hz
Front Chamber: .925 cuFt tuned to 63.46 Hz
7.341 cuFt using a 12" Passive Radiator from Parts-Express
Now, the color chart:
Ported (Vented): Grey
4th Order Bandpass: Orange
6th order bandpass: White
Passive Radiator: Purple (It could be pink.. I'm kind of color blind)
For your hard-core people out there, this was done in WinISD @ 85* F, 75% humidity, and 101.325 Pa...
Please note:: As you alter the tuning frequency on vented boxes, it becomes more "peaky", and won't roll off that flat. This goes the same for the bandpass boxes, as well. If I changed the 6th order bandpass box so the front chamber is tuned to 100hz, the whole line shifts and it has nearly the same response as sealed/vented/passive radiator in the 40-50hz range, and peaks really high in the 100hz range.
Now, with that said, and the chart shown, note, this is just Db gains based on a computer model, and does not include the car's involvement...
As most will tell you, it all depends on your car and your application.
But, I just decided to put this together real quick to show each box's relationship to each other in perfect conditions.