Suit Level 4
The Suit Level 4 Upgrade can only be found in Chapter 7 and that is because you need another Schematic to unlock it. The Intermediate Miner Rig Schematic is located on the second floor in the Equipment Workshop. This will be the point in the chapter when you have the objective “Find the SOS Beacon.” As soon as you head through the Equipment Workshop doors, head down the stairs on the left and the Intermediate Miner Rig Schematic will be sitting on a table in front of you, next to the SOS Beacon. Just like you did for the Suit Level 3 Upgrade, you can then visit a shop to purchase the Suit Level 4 Upgrade for 35,000 Credits. In return, you get 26 inventory slots and a 15% armor boost.
Suit Level 5
Suit Level 5 is the last Suit Upgrade that you will be able to find in just a regular playthrough and it can be found in Chapter 10. As you are nearing the end of the main story, Suit Level 5 will very much come in handy. You will need to find the Advanced Engineering Rig Schematic, which is located in the Locker Room and Showers in the Crew Quarters. Upon entering the Locker Room and Showers, the Advanced Engineering Rig Schematic will be sitting on a bench on your left-hand side.
Head on over to the shop and you can buy the Suit Level 5 Upgrade for 60,000 Credits. The Credits are getting more and more expensive, but the perks are getting better as well. With the upgrade, you will be granted 30 inventory slots and a 20% armor boost as well.
Suit Level 6
The sixth and final Suit Upgrade you can acquire is not in the main playthrough of the game. The only way you can acquire Suit Level 6 is to access it during New Game Plus, which requires you to have beaten the game at least once to unlock this additional content. The name of the Suit is called the Advanced Solider Rig and there is nothing you have to do extra in order to acquire this special Suit Upgrade. After starting New Game Plus, all you have to do is make your way to the shop in Chapter 1 and purchase the upgrade from there. It is simple as that. You also don’t have to purchase it right away if you don’t want to, but the option will always be available in the shop in New Game Plus.
Suit Level 6 costs a whopping 99,000 Credits. While it won’t give you any additional inventory slots past the 30 you would already have with Suit Level 5, it does offer a 30% increase in armor which will come quite in handy for your New Game Plus playthrough. Have fun and good luck on your quest to final all six Suit Upgrades.