I've written up a few DIYs for other forums, i've been drooling over your subies for a while now so it's time to give some love back 
so this is the removal of the steering wheel, the electronic controls, the airbag, the airbag detonator and putting it all back together again. This is for the Forester SH9, 08+ WRX and 03-09 Liberty...
it may also be the same with other models, but I do not know.
BEWARE: you are f@cking with your steering wheel and you’re also disconnecting an explosive charge. If you are not capable or comfortable doing this then DO NOT DO IT.
You will need:
• T30 (Torx/Star) long bit
• Phillips screwdriver
• 17mm socket
• Other tools as required
Step 1: Airbag removal
1.1 Disconnect the battery earth.
1.2 Apply foot to Brake Peddle for at least 20 seconds.
1.3 Loosen T30 bolts from airbag cover, left and right.
1.4 Slowly remove the airbag, exposing the wiring harness and earth.
1.5 Remove earth.
1.6 Remove airbag harness from airbag detonator.
1.7 Put airbag safely to the side with detonator facing the ground.
1.8 Airbag removal complete.
Step 2: Steering Wheel removal
2.1 Unplug electronic control wiring harness and remove leaving the yellow airbag harness intact.
2.2 Apply tape from the top of the steering column cover to the front of the steering wheel – I used two pieces of tape and drew a centre line. [This is used to realign the wheel when you put it back on.]
2.3 Lock Steering and remove centre nut with 17mm socket.
2.4 Pull wheel backwards to remove, [ :lol: - I used a rubber mallet to get the fkr off] ensuring the airbag harness is not damaged - it's easy to hit yourself in the face and end up with a bloody nose
2.5 Steering Wheel removal complete.
Step 3: Electronic control and rear cover removal
3.1 Remove two Phillips head screws, unclip black wiring harness from rear cover and remove rear cover from wheel.
3.2 Remove two Phillips head screws from rear of electronic controls and remove controls from wheel.
3.3 Removal of rear cover and electronic controls complete.
Step 4: Detonator removal
Note: You do not need to do this. The only reason you might need to remove the detonator is if you are shipping the airbag via air DO NOT DO THIS – you cannot send an airbag by any means other than surface mail as it contains explosives.
If you are using this procedure as you are fitting an 08+ STi airbag to your non-08+ STi then you will know by now that the STi detonator has two wiring harness and your version (SH9), has just one harness. You will need to swap the detonator to have a functioning airbag. DO NOT DO THIS.
4.1 Remove the four nuts from the detonator – do not touch the terminals.
4.2 Handle very carefully and do not retain or store an unused detonator. If you need to dispose of a detonator – call your local waste disposal station for advice.
4.3 Detonator removal complete.
Step 5: Putting it all back together
5.1 Reverse above.
Note: Detonator nuts are secured with locktight, when you re-attach the detonator use locktight on the nuts.
Ensure that the detonator is oriented correctly in relation to the airbag.
When re-attaching the Wheel to the steering column shaft use locktight on the 17mm nut.
Enjoy your new wheel, whether it be a DAMD, Prova, STi, or GT-Spec 
