The valve seats in your Subaru engine cannot be replaced. The intake and the exhaust valve seats should be inspected for wear and defects. If the valve seat is found to be damaged, the contact surface can be corrected with a valve seat cutter or reamer.
The valve seats should be corrected when the valve guides are replaced. If valve seat wear exceeds specifications, the heads will have to be replaced.Valve seat wear limit is measured in the direction of the valve axis.