If that's Saul_Good's (not sure of his real name) car in the SOW video it's actually an 05 LGT. Thus not comparable to stock STi lap time. The switch from Megans to proper coilovers at that track could definitely net you that sort of time. Anyone that ever exited the bowl there flat out and crested the small hill that comes after it just before dropping into the next set of turns can tell you how nice it is to have some droop travel there.
Subtracting the mechanical grip advantage of proper working coilovers from the equation for a second lets not forget how important it is just to have a suspension that gives you confidence to find more speed. It's hard to go flat out in a car that feels skittish and nervous everywhere.
A really good driver can be pretty damn quick in anything, but even quicker in something that's working well.