Stealth Girl

Stealth Girl is a perk in Fallout: New Vegas given by Lily if she is your companion. You may obtain Lily as a companion during the quest "Guess Who I Saw Today."

Effects
With this perk, Stealth Boys last twice as long while also granting sneak attack criticals an extra 10% damage. This perk makes a single Stealth Boy last 4 minutes (instead of 2), this has a great synergy with its other effect, increasing sneak attack damage. Any sneak-based character would benefit greatly from the perk. This perk would also help in mssions like the You Can Depend on Me wuest so you can steal from the Gun Runners (Fallout: New Vegas), or assassination kimbal quest.

Behind the scenes
This perk is named after the Stealth Girl, an item in the canceled Fallout: Brotherhood of Steel 2. The Stealth Girl acted as a Stealth Boy, but lasted three times as long.