So I just had an idea relating to Gang Wars:
When a gang decides to declare war on another gang then it would show up on a new leaderboard tab listed as "Wars."
In this tab it can be a list of gangs in war with each other along with the time they have during that week. In order for a gang to win a war against each other then they need more hours in that week than the other gang.
For example the tab could look like this:
There doesn't need to be a reward for the winner but it could go to a new thing on Gang Menus such as "Total Wars Won: 2" or something.