How to unlock Performance Enhanced
Every NERO checkpoint or research site will contain an injector. You choose which ability to upgrade but I would go for an even progression as there is enough to max out all 3 in the game. You'll need to find them all to get the Worlds End trophy. NERO locations are marked on the map with a white bold cross. They can be located by bunker maps, quests or driving around. Most are along the edges of the map so make sure you explore those areas to.