Interesting as I probably need a new steering rack too since I got this slack in the steering.what year is your forester? the sti and even the wrx steering racks are huge improvements over the forester one... the sti one needs to be out of an 04 to bolt right up, if you find an 05+ youll need the crossmember as well. and im pretty sure any year wrx rack bolts up. since performance doesnt seem to be a huge concern, you can find a wrx one for much cheaper!
I changed the steering rack bushings. It did help a bit but not much.