That motor is a horizontally opposed four cylinder. Typically an EJ20 (2.0 liter) or EJ25 (2.5 liter) is what is found in subaru cars. The history behind this engine design dates back to the naka aircraft company that produced planes for Japanese during ww2. Still used in aircraft today, the subaru engine is a great performance motor with extensive durability. Commonly swapped into light aircraft, the ej20 and ej25 are great for power and balance. I get jollies knowing my car has an airplane motor.