Hey John!!
The box is about 1.70cft and tune to around 40hz.
If you thinking about buying a amp and subs, you maybe better buying a use sub for around $300 to $400
You can probably change the subs and re-tune the box, just depend on the subs you buy, make sure you buy the subs with the same ohms.
You can check some subs here.......................
http://www.partsexpress.com/webpage....ctGroup_ID=847