The upgrades to the K-9000 Cyberdog Gun are found in the X-13 Research Facility. These upgrades are unique in that they upgrade the gun into two very different styles of weapon, making it one of the most unique weapons in all of FNV.

Quick tips before setting off to get the upgrades:

• Old World Blues DLC required. The gun as well as its upgrades are all located at the Big Mountain Research Center, which is where the Old World Blues DLC takes place.
• Stealth Suit MK2 required. To gain access to the corridor where you can find the upgrades, you’ll have to fully assemble the Stealth Suit MK2. Luckily, all of its parts are located in the same facility. Guide on assembling the full suit here.
• FIDO. If you only have one of the two K-9000 Cyberdog Guns, you’ll have to decide whether you want the upgraded base variant, or the special FIDO variant. Guide on getting both of the K-9000s here.

Where to find the upgrades

First, you must make your way to the X-13 Research Facility, located on the western edge of the map, and assemble the Stealth Suit.

Once you’re inside the facility with the Stealth Suit MK2, go straight and follow the hallway past all of the rooms, until it leads you to a large, open room with a force field instead of a floor.

At the opposite end of the room, there is a large hermetic door with a terminal next to it. While the Stealth Suit MK2 is equipped, you can interact with the terminal to unlock the door (which is also an elevator). Once the door is unlocked, head on through.

Once past the door, take the metal catwalk straight ahead of you and take the first door on the right.

This will lead you to a large, open room. On your left, you should see another catwalk that gets you to the second part of the room. Walk across.

Once across, walk to the end of the room and look left, you should be able to see a terminal. Get over to it and interact with it.

Next, simply select the “Check out this mod I’ve been working on” option. This will give you the Resla Roil upgrade holotape. 

Exit the terminal and turn around. You’ll see a door. Go on through and take the first door on your right (the one with the “OFFICE #2” sign next to it). Open it and head inside the room.

You should see a working terminal in the opposite corner of the room. Walk over to it, interact with it and select the “Suggestion.” option. Doing this will give you the Mentat Chow upgrade holotape.

Now that you have both of the holotapes, you may exit the facility and travel back to the Sink. Interacting with the Sink Artificial Intelligence will give you both of the upgrades and you may attach them to the K-9000 Cyberdog Gun.

Benefits of the upgrades + Tips

• The Mentat Chow upgrade is especially important. With it, you’ll be able to mitigate the fire rate penalty of the Trigger Discipline trait, which will drastically decrease the spread of the weapon.

With both of the upgrades installed, the weapon will have a DPS of about 270, which is higher than the base Minigun’s 240 DPS and almost as high as the fully upgraded Minigun’s 300 DPS, while consuming far less ammo.