I doubt that you can buy the OEM breather hoses from Subaru anymore.  The double curve hoses are particularly hard to replace by shopping on line because the offset of the two ends is unique to the car, and unlikely to be made by Gates and others.  So I improvised for a fraction of the retail prices that I see listed on Ebay, by using 3/4" diameter high temp silicone coolant hose in the multilayer type, brass barbed elbows and then enough 7/8" clamps to make those single and double curves.  Once the original hoses crack, then your engine is not going to run well.  So I wanted to replace with the new and pliable hoses to head off that potential breakdown.

The engine develops more power and responds quicker as a result of improving the suction in this breather system, for some odd reason.