Here is a 1989 Williams Black Knight 2000 playfield set that just came (2017) in for restoration.  Like most SYS9/SYS11 playfields (like High Speed, Banzai Run, Swords of Fury, Taxi, etc.) they take a lot of labor hours to restore.  No insert decals, stickers or overlays were used in this restoration.  Everything was painstakingly masked off (using our Roland digital mask cutter) and airbrushed.  Some of the finer details had to be hand painted but 90% of the restoration was airbrushed.   The average SYS11 playfield restoration is about $1000 and will take 90-100 labor hours to restore.   Please note:  These SYS 11 playfields take a higher skill set to restore and very few of the playfield restoration guys have this skill set.  If these so called playfield experts do attempt to restore your SYS11 playfield, they will just  use insert decals and stickers/overlays.