Courtesy Al Gainey & Alex Shikhmuradov.

Tools required:

3/8 drive ratchet
Deep 14mm socket
Standard 12mm socket
Open end 12mm wrench
Standard 14mm socket
Open end 14mm wrench
Standard 17mm socket
Various 3/8 ratchet extenders
Can of WD-40

Open the hood and unbolt the 12mm nut that holds the pitch rod to the engine. Pull out the long 12mm bolt and pull that bone looking thing out of there. This will let the engine lift straight up when you jack it up.

Set the emergency brake and put blocks behind rear wheels. Get yourself a 1 ton or more hydraulic floor jack and 2 jack stands. You will also need a least two sections of cut 2/4 lumber. Each piece should be approximately 5 to 6 inches in length. Place one piece of wood on the floor jack and place the floor jack in the center of the engine crossmember. Jack up the front of the car to the limit of the floor jack. Place one jack stand under each sway bar mount. Lower the car slowly until it rest on the jack stands. Remove the floor jack and slide under the car.

First unbolt 6 14mm nuts that hold the header in it's place (3 on each side). Drop the exhaust manifolds down. Don't pull them all the way down as there is an O2 sensor in the cat and you don't want to stretch the wiring.

Then remove the main 14mm nuts on each side on the inside of the bottom of the engine crossmember (#1 nut in the above picture). Remove these. Then remove the 14mm bolts on left and right engine mounts that attaches them to the block (#2 bolt in the above picture).

Now place the floor jack under the oil pan. Make sure you have a piece of wood between the oil pan and the floor jack. Don't worry about the oil pan, the engine is very light. Very slowly and very carefully jack up the engine from the crossmember. Jack up the engine as high as you can but remember, all of your hoses and wires are still connected so use extreme care when raising it. After you have raised the engine to its maximum height, place the second block of wood between the oil pan and the crossmember. Now slowly lower the engine onto the wood block. this will allow you the room needed to access the rear mounting bolts. You will have to use the box end wrench to remove the two rear motor mount bolts.

Sorry, no picture here. Just stick your hand there and try to find it. It was impossible to take one.

You should be able to remove the mounts now. Remove the two 14mm nuts that hold the metal plate to the engine mount. Put them on your new STi mount.

Install the new mounts in reverse order. Jack up the engine a little bit and remove the block of wood from between the oil pan and crossmember. Lower the engine to the point that the studs of the motor mounts are just touching the crossmember. The mounts fit inside a special square 'cup' on the topside of the crossmember. Make sure that the mounts are perfectly flat against the top of the crossmember before you torque them down. If they don't, jack up the engine back up a bit and ask your friend for help. He will have to move the engine and you need to navigate him and drop the engine in between those square 'cups' Also for you people out there that believe that all bolts should be torqued down to 300 foot pounds, be aware that the the block is made of aluminum. Don't overtorque the bolts! Put the bone looking top engine mount from the first picture back in it's place and secure it with the appropriate 12mm bolt and nut. Jack up the car, remove the jack stands and lower the car back where it belongs.