What I put in: NGK Iridium IX (LFR7AIX) one step colder plugs.
Tools you will need:
10mm socket or ratchet - to remove intake and battery.
12mm socket to remove coil pack bolts.
1/4 drive socket wrench with 12mm socket for the two rear coil packs (It's tight).
5/8" spark plug socket
2", 3" and 12" extension for 3/8 drive wrench - For removing the spark plugs and coil pack bolts.
A knuckle extension.
Anti seize - I use this on the spark plug threads
Dilectric grease - I put a dab on the top of the spark plug where the coil packs wire touches the plug
Do the spark plug change when the motor is cold so you don't risk striping something or burn the living daylights out of yourself.
First start by removing the air box and all of it's plumming up to the inlet hose. First start by undoing the hose clamp that connects the airbox rubber hose to the inlet with a screw driver. The unsnap the air box clamshell clips and pull the back half of the airbox out of the engine bay. Now with a long extension remove the two 10mm bolts that hold the airbox to the fender. Don't forget the 1 10mm bolt inside the airbox as well.
Once the airbox is out go ahead and remove the battery tie down with the 10mm socket. Once that is out of the way remove the batt cables. Remember to undo the negative first and then the positive battery cable so you don't risk gettin a zap. (Installing will be positive and then negative).
Getting the airbox and battery out will make for alot more room as things are tight as is. Doing the WRX/STI some will take out the window washer bottle, but that is not needed for the LGT.