Thanks everyone. I am going to mock up a box to show the rhythmic f15hp size and see if I can live with it. If not, I am probably going with the SVS 13 ultra. It is the smallest of the crop and still seems to get fantastic reviews. All of your input has been extremely valuable. Sounds like between DVS, Rhythmik, and PSA, I really can't go wrong. PSA is attractive given the history of the founders but all of their subs seem on the large size compared to the two others brands and models I have narrowed it down to.