I think all the original SV kits Danny sold would have had the SW12 16Fr's. When your run them in parallel, you end up with a 8 ohm load (actually a bit less due to the fact they are not the full 16 ohms).
Not sure where you got the kit but if it is a kit that was pieced together (not purchased as a complete kit from Danny), possibly you ended up with the 8 ohm version. If that's the case, then your amps are seeing slightly less than a 4 ohm load so they'd be outputing signifigantly more power allowing the woofers to bottom at very high levels
jay