If the CEA measurements are correct, it really is a very good value, especially when you consider the footprint for the 3X12. In fact, it would best the impressive RBH G2 SX1212PR and is only half the price. $/SPL, its gives the PB13 Ultra a serious run for its money. I'd love to see these confirmed by Josh. There really isn't any variable tuning in the ordinary sense of the word though. Yes, it supports a sealed mode, but I have always taken variable tuning to mean multiple ported tuning points. In the sense the XTC is variable tuning, any ported sub could be considered likewise, because you can seal any port and alter the performance.