OK I found out today. I was in the SS today and I was told that it comes standard from Holden however they do get a better brakes package. Didn't ask about the Fords, however I assume it's much the same.
As for the weight yeah it probably weighs a bit more, probably due to the fact that they carry a lot around in the boot... and there's the computer in the car, the ANPR gear etc.
So perhaps we don't even lower them, at least it wasn't mentioned to me... They might just look low because of the extra weight, i'm unsure.