The 60-inch subwoofer absolutely has the capability to produce SPL levels well above 180 dB. It is simple math and the laws of physics.
Actually, before designing it, we looked at a comparison between a large number of conventional subwoofers, or a single giant one. After we did the math, the obvious choice was the one giant woofer. It's output displacement is comparable to 160+ ten inch woofers. It can move a lot of air!