I think the BOSS/CS fascia comes with wiring connectors intended to get power from the stock GT fog harness which is H10 style not H11 like the pony pkg fogs.
You may have to buy the H10 harness without switch or swap connectors on the fascia wiring kit.
Edit: looks like they have a proper adapter instead of buying a new harness V6 Mustang Fog Light Converters H11 to H10 Set (2005-2013) ? Starkey Products
You just have to confirm with AM that their fascia wiring kit has plug ends instead of something else (like splices).
Since you already have fog lights you will need:
-GT or GT/CS front bumper fascia
-GT/CS or BOSS lower fasica
-GT/CS fog lights (2)
I bought my parts from my local Ford dealership. Shipping was free and I didn't have to pay a cent until I got to look through the boxes. If you want to use your stock grille instead of the Saleen one you will need a grille surround. Also if you want the lower BOSS splitter that sticks out below the lower fascia, that is an addition component.
To install, you will need to remove the radiator cover, current front bumper fascia and disconnect your fog lights. Install the new lower fascia into the new front bumper fascia. Remove the front caps from the new lower fascia and install the fog lights. Install your new grille. Route fog light wiring harness so that it will connect to the new fog lights. Install new front bumper fascia assembly. Connect wiring harness to new fog lights. Reinstall old radiator cover.
If you have any questions, let me know. I don't have the exact part numbers in front of me, but I can find them if you'd like. Yes, you will need to paint the bumper if you don't get a Silver takeoff. Mine cost about $300 to get it painted. In total, it cost me about $1500 to swap the front end of my car, but yours might be a bit cheaper by going with the Saleen grille and not getting the lower BOSS splitter.
2012 MCA V6, Kona Blue, Stone Leather, HIDs, Performance Pack, Reverse Sensing, Interior Upgrade, Comfort Pack, Medium tint, Carbon fiber splash guards, JTL oil separator, Borla ATAK AB exhaust, American Muscle 1/4 window louvers, Hood spear decals, Raxiom rear tail lights, Steeda LCAs, Ford Racing panhard bar
Order: 6/28 VIN: 8/23 WS: 8/30 Build: 9/6 Arrived: 9/20 Pickup: 9/22