You didn't mention what model bike, but generally if done properly, the forks are lowered in the tripple clamps and the "dog bone" (link between the rear shock and frame) is changed for a longer one in the rear. This lowers the front and rear the same amount keeping the steering geometry about the same as stock. They probably still have the original dog bone, so all it should take worse case is a couple hours labor in the shop. A new/used stock dog bone probably isn't too bad if needed as well. Ask the sellers how it was done.