Depends on the model forester.
The SF series need GC8 front and GD rear while the SG series have GD all round, this is for coilovers with camber tops. GD can fit in the SF but the camber top will be facing in an odd direction.
Oh and for struts, as said any model wrx or sti up to the 05+ STi which need to be modded (I had this before I went for coilovers)