Anywhere between +38ish to +45ish. Depends heavily on your tire size, both width and height. Running 'coilovers' increases the amount of inboard clearance. The swaybar link up front has a very long stud that will need to be trimmed to be sure of clearance, or you can replace them with shorted studs.
I run 19 X 10s on my '12 LS. 35 mm et on front and 48 mm on rear. 275 35s on front and 295 30 on rear. VERY pleased w/ this set up.Sportline springs - 2 " drop on rear and 1.5" in front. So you might check into these offsets.