lowering 911sc

I want to lower the front and back by 1/2". It is above spec. My question is: isn't there a factory adjustment on the rear that would bring it down an inch WITHOUT resetting the torsion bars? if so, how is it done. and 2, how much will 1/2" down effect my alignment?

On my 88 911 i had it lowered,front and back,is my undersatanding that the car must be align after,is it ?in my case it was done wrong, end result my rear tires were gone in 500 miles,and of course the shop that did the job refuse to stand at their work.