First:  This is a difficult job, if you have no talent for this (nuts, bolts, soldering and stuff) don't do it.  You can damage your stereo and car electronics or scratch or crack the plastic frame around the stereo.  I am not responsible for you actions or inability.  This job should take an hour or so.  You'll need special tools (long phillips screwdriver with  magnetic end), small stub screwdriver (possibility a right-angle phillips screwdriver and a flat screwdriver, rag (for when the screws drop), drill and a drill bit to enlarge the holes, soldering gun and solder, black electrical tape, a radio (I got a 25 watt per channel for $160 and 4 Polk speakers.  They can't handle the bass I want but the stereo has outputs to a sub woofer.
I did ask for a stereo upgrade when purchasing the car, I was told $350 for a CD.  NOT THINKING, I said yes.  But only a CD player was added to the 10 watt stereo.  It was removed a few days later by the dealer.  I got $300 back (it was discounted the dealer said.  The dealer also said the FACTORY ALARM was specially wired into the car.  The BOX and it's snap in connector will be shown.  Oh well.  Maybe the alarm and the stereo will show up on E-bay.

Here is the way to get to the radio.  First you get a flat screwdriver and CAREFULLY pull up from the back.  DON'T SCRATCH the wood grain!  Go up from the rear and pull UP then pull away from the front.

This is a stereo pin out by Joe Holly, Click here to see it.

 
  Now you have the shift trim off.  Put it some place you won't sit on it!  I bet this is a $65 piece of plastic.

Now you need to remove the two big screws holding the little cup in place.  Put the screws in the cup.



  You will need the keys to put the car in drive.  PARKING BRAKE... EVEN A STONE BEHIND THE WHEEL TO KEEP YOU FROM ROLLING.   The car will BEEP when the keys are in the ignition.  Get use to it or put it back in park with the key out every once in awhile.

This little bugger is the ash tray  Pull out the tray and push down on the top to remove the cup.  Now there is ONE screw in the back and two (snub screwdriver) on top.  Keep them in the ash cup.


 

With the ash tray out you can now remove the outside trim and cup holder.  From the bottom, carefully pull up and at the top right pull the plastic dash from the trim to get that section by the cup holder out.  It comes out and down.  You may need to move the windshield wipers arm down. 
CAREFULLY TAKE OUT THE TRIM, NO REAL PULLING IS NEEDED.


 

With the trim off,  you can see the 4 screws holding in the stereo.  That box is the (as the box states) factory alarm.  I paid $176 for that box.  I am looking for a auto starter.


 

Two ways.  You can take the screws off with a right angle screwdriver and drop the screws into never-never land.  Alas the rag to keep dropped screws from going down the sides of the carpet.  Better bet.  Take out that whole frame.  Here's the 2 screws holding the whole assemble in the car.  This also shows the two screws holding the plastic holder (where the CD was).  You have to hold the back open and get the end pins while pulling it out.  I found it helpful to have that out.  You may not.  Try unscrewing all the screws on the left of the frame a bit to give you that extra space.


 
 

Shot of the right side screws.


 
 

With a magnetic screwdriver or use a rag at the bottom to catch them as they drop,  get the 4 side and 2 bottom screws. There is one or two screws on the alarm module. That can swing forward and hang there. The whole assemble comes forward.  There is still a cable running from the top air conditioner control so even taking all the wires off, the system will not come far from the dash.  It will come out enough to get to the screws.


 

A tangle of wires.  FIRST:  to get the stereo in you have to do all the wiring soldering. (unless you get the adapter from www.crutchfield.com) and tape them.  You must PUSH in the stereo (in my case one with a removable front) all the way in.  It will sit flush with the other items.   SECOND:  you have to drill the two matching holes on the stereo a bits closer together.  Watch were the metal bits fall.  I had a Sony 10 pack from my former Jeep.  I added that at this time as it needed to be plugged into the stereo's antenna and stereo's power wires.  You see the "alarm" box hanging at the bottom that is specially wired, hence can't be removed and resold.  DO NOT UNPLUG IT, you might need to reset all your remotes.

When finished you can plug in everything, push back the unit and try it to make sure everything is right.  MAKE SURE YOU DON'T CATCH ANY WIRES ON THE METAL FRAME THAT GET SCREWED TO THE DASH.  That will cause a short and trouble.  I would not put the 10 pack behind the stereo.  It gives less air space and there is a reset button on that unit that might need to be pressed if the unit gets "confused" to reset it.  These units are great.  They work through the stereo's radio at an empty radio channel.  Newer units are cheaper and work off specific stereos but those units seem to be priced at $250 and up.  This radio changer unit cost under $200.


 

Oh baby.. where is that blue wire?   Lots to get stuffed back here.  It all fit!  Without the RF adaptor for the 10 pack, you won't have this much of a mess.


 
 

All back together.  After missing a few screws (they seem to fall in a notch in front of the shifter and the electronic box) these system was tested and everything put back together.  Next time (I may move that 10 pack unit to under the dash) it should only take a half hour.  The electronic store in New Jersey had a $50 fee to install the stereo.  Depends on your ability and if they break it, they replace it.


 

The Alpine stereo.  With the new speakers alone, the sound was an improvement. This helped a awful lot!  But the little Polk speakers aren't up to the Jeep Infinity stereo system.  Hummm

Added by reader in 2008
Although I have a 2001 Legacy, the layout seems to be exactly the
same.  I found that a ratcheting offset screwdriver (picture attached)
worked "well" for those top screws on the ashtray.  That thing is a
Pain In The ASS!  I also found a magnetic screwdriver to be invaluable
as I dropped screws several times.

  One comment though is that I think Subaru had two different sets of stereo wiring color codes that year, since your .doc file and some other references I found for  2002 Outbacks online didn't match my car.  For addition to your web site, here is what was in my car:

Car Radio Battery Constant 12v+ Wire: Blue/Yellow
Car Radio Accessory Switched 12v+ Wire: Yellow/Red
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Green
Car Radio Ground or Nothing:  Black/White
Car Radio Antenna Power: A 2nd green wire, may be taped together with the Black/White
Left Front Speaker Positive Wire (+): Brown/White
Left Front Speaker Negative Wire (-): Green/Black
Right Front Speaker Positive Wire (+): Red/Yellow
Right Front Speaker Negative Wire (-): White/Black
Left Rear Speaker Positive Wire (+): White/Red
Left Rear Speaker Negative Wire (-): Red/Green
Right Rear Speaker Positive Wire (+): Blue/Green
Right Rear Speaker Negative Wire (-): Red