So we recently bought a 2010 Legacy fully loaded with everything except fog lights.
I wanted to rectify this but didn't want to spend the $300 the dealership wanted for the factory fog light kit. I came across the Morimoto XB LED Type S (there is a type S that fits the Subaru and others, and a Type T fits Toyota and the like.) I decided i'd rather have the higher light output than the factory fogs and tried to round up the OEM components individually as I did not need the factory light housings/bulbs.
I was told by a dealer that the mirror/fog light switch was ONLY available in the accessory kit, not on its own. I found this to be untrue when I found the parts elsewhere from a supplier in the U.S. (I was shipped the wrong factory blank switch initially but QuirkParts was very quick to rectify that and send me the proper switch at no charge. Excellent online pricing, best I found and great service btw.)
The install was super easy, I will provide a detailed parts list with links to the required parts and pricing below. The morimoto fogs come with mounting bolts to fit the factory nut insert clips (clips not included). This is a great way to install a brighter fog light kit on your fifth Gen without having to buy the factory kit. If you already have fogs on your car the Morimoto LED fogs are plug and play and a direct fit with OEM fitment and wiring connections.
The regular instructions supplied by Subaru at the following link work excellent: http://techinfo.subaru.com/proxy/72656/pdf/072656-072655-063750-H451SAJ000.pdf
Parts required, quantity and price (this is for 2010 Model year):
Morimoto LED XB Type S Fogs $160 (Qty: 1 set) Plus optional yellow Lamin-X ($10):
http://www.theretrofitsource.com/led-lighting/morimoto-xb-led-fog-lights-type-s.html#.VFzZ5zSoq7s
OEM Fog light/mirror switch $47.53 (Qty: 1) P/N H4510AJ000
http://www.quirkparts.com/oe-subaru/h4510aj000?search_str=H4510AJ000
OEM Fog light Trim insert for driver's side $23.22 P/N 57731AJ20A (Qty: 1)
http://www.quirkparts.com/oe-subaru/57731aj20a?search_str=57731AJ20A
OEM Fog light Trim insert for passenger side $23.22 P/N 57731AJ19A (Qty: 1)
http://www.quirkparts.com/oe-subaru/57731aj19a?search_str=57731AJ19A
OEM Fog lamp Assy Nut $0.64 P/N 902510034 (Qty: 2)
http://www.quirkparts.com/oe-subaru/902510034?search_str=902510034
OEM Relay $4.73 P/N 82501AG05B (Qty: 1)
http://www.quirkparts.com/oe-subaru/82501ag05b?search_str=82501AG05B
Total cost: $269.98 plus shipping.
Very few tools required, a 10mm socket to install the mounting bolt for the fog, a flat head screwdriver for removing the lower bumper shroud plugs, a smaller shorter flat head to release the mirror switch clips, a phillips for removing the one lower shroud plug and the dash trim at the mirror switch.
The connectors on the fogs are already pre-wired and crimped on the wires all you have to do is determine polarity and then insert them into the supplied connector that matches the factory version. Take your time with a screwdriver lining up the connector pins when trying to connect the two plugs.
Remove the two front plugs on the bottom of the bumper and the one phillips plastic plug facing the opposite direction inboard towards the engine. This gives enough space to get your hand behind the factory blank fog light opening covers, it doesn't take a ton of pressure to release the tabs and remove those black blanks. The rest of it is just following the instructions in the supplied PDF link at the top of this post.
http://i.imgur.com/gIzOeMQl.jpg
Morimoto fog installed:
http://i.imgur.com/Nh054U3l.jpg
Light color without Lamin-X:
http://i.imgur.com/e0Ihf5il.jpg
Installed with bezel and Lamin-X:
http://i.imgur.com/eJ8bKHsl.jpg
Factory Low Beam light output:
http://i.imgur.com/5t63g6Dl.jpg
Low beam and Fog:
http://i.imgur.com/CpNOAahl.jpg
http://i.imgur.com/PuZ35d2l.jpg
The cut-off/output. I need to adjust the driver's side up a bit. I was playing with the adjusters and started lower on the driver's side to avoid glaring other drivers in the face.
http://i.imgur.com/GgcgV22l.jpg