L (Turbo) And 3.0 L Model

Remove the battery and battery carrier.
Remove the air cleaner case.
Detach the connector from ignition coil.
Remove the ignition coil.
- 2.5 L turbo model
  
  Fig 1: Identifying Connector From Ignition Coil (2.5 L Turbo Model)
  Courtesy of SUBARU OF AMERICA, INC.
- 3.0 L model
  
  Fig 2: Identifying Connector (3.0 L Model)
  Courtesy of SUBARU OF AMERICA, INC.
Remove the spark plug with a spark plug socket.

Fig 3: Removing Spark Plug
Courtesy of SUBARU OF AMERICA, INC.
Tighten the new spark plug lightly with hand, and then secure with a spark plug socket to the specified torque.
Recommended spark plug:

2.5 L Turbo model

NGK: SILFR6A

3.0 L model

NGK: ILFR6B

Tightening torque:

21 N.m (2.1 kgf-m, 15.2 ft-lb)
Tighten the ignition coil.
Tightening torque:

16 N.m (1.6 kgf-m, 11.7 ft-lb)
NOTE:
- Be sure to place the gasket between the cylinder head and spark plug.
- If the torque wrench is not available, tighten the spark plug until gasket contacts cylinder head; then tighten further 1/4 to 1/2 turns.