If you fit an exhaust to your naturally aspirated Subaru engine in which the header pipes point directly backwards after leaving the cylinder head, you will probably have a problem with the radiator return plumbing, where it joins the coolant inlet on the thermostat housing. It will be in the way of the exhaust.
  This adaptor rotates the coolant inlet fitting so it points backwards instead of to the right, so a 90 degree hose can be fitted, and the plumbing routed away from the exhaust.

Pictures coming soon...