More like 1/2"
B___S___T
The car sits on the spring (S), and it's only the shock tower side (T) that is getting lowered. The balljoint side stays the same. Since only the one side is getting lowered one inch, the car only drops about half that. Purchasing the negative wedge kits puts the balljoint at a better angle, making it wear better with this modification, and also allows the arm to be lowered a bit further without bind.
Good Luck!