New sub enclosure Please help

[CrossfireExpedition]

Im thinking about building a new sub enclosure but i want to try aeroports...i really dont know anything about using them. If I build a 6.5cuft enclosure, to tune it to 40 or so hz using 6in ports i came up with this:

6.5 cuft enclosure

2-6in ports 10.25 L

tuned to 40hz

or

6.5 cuft enclosure

3-6in ports 17.5 L

tuned to 40hz

Does this right to you, any help is greatly appreciated.

Thank You,

Brian