As this Game does not need much GPU Power, usually you don't need a SLI Profile.
But if you want to Downsample and crank everything up - you might need the SLI Profile.
Note: This Game has a FPS Cap (Vsync) @60fps
--------------------------------------------------------------------
=> SLI compatibility bits: "0x02C00045 (Batman:Arkham Origins, Batman:Arkham City,...)"
--------------------------------------------------------------------
Nvidia Standard (SLI Off): GPU1= 73%; GPU2= 7% @29fps

Fixed SLI Profile (SLI On): GPU1= 89%; GPU2= 80% @56fps

0. Download [www.nvidia.com] & install the latest NVIDIA Driver
1. Add "injustice.exe" to your NVIDIA 3D Profile Settings
( ->Nvidia Settings -> Manage 3D Settings -> Program Settings --> Add)
2. Download [www.guru3d.com] & open NVIDIA Inspector (note: also extract "CustomSettingNames_en-EN.xml")
2.1 Go to “Driver Profile Settings” --> Set Global Driver Profile to "injustice.exe"
2.2 Then set "SLI compatibility bits" to "0x02C00045 (Batman:Arkham Origins, Batman...)"
2.3 & set all other settings as shown below... --> Apply changes
3. Enjoy Injustice: Gods Among Us with SLI enabled

Unfortunately after installing a new Nvidia Driver, you have to set your SLI Profile again!
Even with the "Express Installation"... :(
(But only the SLI Profile Settings, the tweaked Settings stay the same.)
--> You can "prevent" that by Exporting all customized profiles (with Nvidia Inspector) and import them back after the Nvidia Driver Installation!

1. Go to Display ->Adjust desktop size & position ||| 1.1 Go to Display -> Change Resolution
1. Set everything as shown above and click Apply.
1.1 Select your native resolution and click Customize.
=> There you tick Enable resolutions not exposed by the display & press Create Custom Resolution.
2. Create your custom resolution:
It is important that you set the Timings Manual as shown above.
(The Pixel Clock should not go above 165MHZ!)
2.1Hit TEST
--> if you set everything correct, your Desktop will be shown in the resolution you just set.
It is important, that you click Yes if you see your Desktop in the desired resolution.
==> This is for adding the resolution and not for setting it up for your desktop.
3. Set your custom resolution in-game & enjoy Injustice @2880x1620 / @3840x2160
Note:
Some monitors do not go beneath 56Hz, even if they are able to! That is driver related & can be fixed!
(My 24" Samsung needed the EDID Monitor Hz FIX[www.oc-burner.de] for 3840x2160 @54Hz, to work properly!)

I5 2500K @4500MHz
GTX 460 SLI @840MHz / 2000MHz
16GB DDR3 @1600MHz
120GB SSD
Win 8.1 Pro 64bit

Tested on the following NVIDIA Drivers:

• 331.93 Beta
  
• 332.21 WHQL
  
• ...

--------------------------------------------------------------------
PLZ Rate if you like... :)

& follow me for more SLI Fix Guides => click