NickB, for me I get more IMPACT from movies/music via my M80s and now VP160 than I ever have from my SVS PB13 Ultra. That impact, chest thump is from a higher frequency than most subs are set up well to play, either due to design, setup factors or any other numerous points. This desire for impact (as well as a little better lower midrange warmth) is what led me to purchase a full range speaker for my mains and now for my center. I get much more rumble, seat of the pants feel from my sub but again this is also due to my set up, crossover points etc.
This is a great answer. So chasing after the biggest and baddest sub for impact is sort of a waste of time. Not to say that there isn't a justification for the SVS PB13 Ultra. If you have a large room and/or want that sub 20Hz frequency response then that is a reason for a sub like the Ultra 13.
So you are saying that the chest thump is over 80Hz? What are you crossing over your center and fronts at?