This particular value can't be changed in the editor, you will need to use the PAK extractor to manually extract the file. The file in particular you are looking for is Data.txt in
Shared.PAK/Public/Shared/Stats/Generated/Data/Data.txt
The mod needs only contain the line(s) you want to change.
To save you the trouble though, someone has already made a mod doing just this at
http://steamcommunity.com/sharedfiles/filedetails/?id=1149996340&searchtext=
