Spider,
First, thank you so much for you great responce. DIYsubs.com is fantastic. It answered a lot of my questions. Now I have to play with that spreadsheet model to see how all the relationship work. But I do have a question for you. Your responce to my 50/50 music/HT usage was to use a sealed box. Now from most of the responce curves I have seem a sealed rolls off very gradually starting around 40-50 hz while a vented is realtively more flat down to its tuning point and then drops off fast (I think I said that right). What sonic qualities do you feel make up for the roll of a sealed (is that why you said a large enclosure to counter this)? Does room gain fit into this roll off better than a flat responce?

The way these kits can come everybody should make their own subs.