How to Install:
Import zip file into ME3Tweaks Mod Manager, then apply mod.
Uninstall:
Click 'Manage Target' and then disable or delete.
Notes
For the armour in LE2, there is now an optional file that adds the Aria outfit as a chest piece instead of a full set. This is so that you won't get a radio/breather sound effect whenever Shepard speaks while wearing the armour (casuals are unaffected).
1) Go to Documents\ME3TweaksModManager\mods\LE2\Aria Outfit for Femshep LE2\DLC_MOD_LE2AriaBlackOutfit\CookedPCConsole
2) Delete the original BIOGame.ini file
3) Drag the new one you just extracted into the folder
Don't forget to refresh your mod library and reapply the mod in ME3Tweaks after all this!
This doesn't get rid of the other armour pieces however, so you can also install Invisible Vanilla Armour Parts - IVAP (LE2) with this so that there isn't any clipping.
Update 09/02/21: There is now an optional file for LE3 that adds the outfit as a chest piece instead of a full set as well, giving more leeway into mixing/matching other armour pieces.
1) Go to Documents\ME3TweaksModManager\mods\LE3\Aria Outfit for Femshep\DLC_MOD_AriaBlackOutfit\CookedPCConsole
2) Decompile Default_DLC_MOD_AriaBlackOutfit.bin through ME3Tweaks
3) Delete the original BIOGame.xml file in the Default_DLC_MOD_AriaBlackOutfit folder
4) Drag the new one you just extracted into the folder, then recompile Default_DLC_MOD_AriaBlackOutfit
If you don't know how to decompile/recompile, then just follow this short tutorial.
This will also have some clipping, so if you don't like that, install Invisible Vanilla Armour Parts - IVAP (LE3).
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Thanks munchyfly and B.LU for help with troubleshooting.