Those SF71's aren't the ones that are 1 series fitment. Those are different offsets that will rub on your car but they used them to show people how it could potentially look. So they look alot better / more concave when ours aren't.
You can get the same kind of drop height by buying any coilovers and setting to your desired level. Springs may work as well but then you won't be able to go lower or higher.