Gang Wars are a side activity on Grand Theft Auto IV's DLC, The Lost and Damned. An achievement/trophy "Full Chat" is awarded to you if you have raised Terry and Clays toughness level to 100% each through missions and Gang Wars, and weapons are unlocked in your safehouse as you complete more and more Gang Wars, but enemies will be stronger as you progress.

A list of weaponry that unlocks in your safehouse: