How machine modules work in Probably Stolen: Performance, Efficiency and Quality effects, bay space, installation, stacking and the best upgrade order.
Probably Stolen Modules Guide: Machine Upgrades
Machine modules are Probably Stolen's real upgrade system. They are not Workshop mods and they are not perks. They are physical parts you place into a machine's module bay to change its performance, power draw, or output quality. A machine with the right modules can be twice as useful as the same machine with none.
This guide explains the three module families, how the bay works, and the order to upgrade. The module list and stats page has the numbers; the bay expansion and extractor page covers the hardware.
The three module families
| Family | What it changes | Best used for |
|---|---|---|
| Performance | Speed or output rate | Machines that are too slow |
| Efficiency | Power or input consumption | Overnight machines and multi-machine shops |
| Quality | Output quality | Chemistry, printing, genetics, hydroponics |
A standard module is reported to have a value of 70 credits. The actual price depends on the seller and the machine, and the effect is not the same in every machine. That is the most important rule on this page: a module's headline percentage is not its machine-specific effect.
Machine-specific discounts
Community testing reports that some machines only receive a fraction of a module's effect:
| Machine | Performance | Efficiency | Quality |
|---|---|---|---|
| 3D Printer | — | — | 25% |
| Mirage Projector | 25% | — | 50% |
| DNA Manipulator | — | — | 50% |
| Hydroponic System | — | — | 50% |
| AgeWell | 50% | 50% | — |
The dash means the effect is not documented for that family, not that the machine is incompatible. Treat the table as a guide for where a Quality module is worth the most, and test the actual output before buying a full set.
A Quality module in a Hydroponic System or DNA Manipulator can be worth twice as much as the same module in a 3D Printer. If you are short on modules, put them where the discount is smallest.
How the module bay works
Each machine has a grid-based module bay. The standard bay is 7 × 5, or 35 cells. A fresh machine does not expose all 35:
| Bay stage | Usable cells | How to reach it |
|---|---|---|
| Initial | 26 | Default; corners and centre cross blocked |
| Stage 2 | 31 | One expansion |
| Stage 3 | 35 | Two expansions |
The blocked cells are part of the bay's shape, not empty space you can ignore. A large module may not fit until the bay is expanded. That is why a 2 × 2 module can be impossible to install in a fresh machine even though the total cell count looks sufficient.
Each expansion is reported to add 100 credits to the machine's value. That makes the expansion an asset as well as a convenience, but the real benefit is fitting more modules.
Installing and removing modules
- Open the machine's control panel.
- Select the module bay.
- Place the module on a free footprint.
- Confirm the installation.
- Check the machine's stats before starting a batch.
Modules have shapes, not just a single cell. A 2 × 2 module needs a 2 × 2 free area. Rotating or rearranging modules may be necessary to fit a new one.
Removing a module normally requires a Module Extractor. The Basic extractor has limited uses; the Advanced extractor is reusable. See the extractor guide for costs and sources.
A powerful module you cannot fit is worse than a cheap module you can. Check the bay shape before buying a 2 × 2 part.
Special modules
Two special modules are well documented by community testing:
Corrupted Module — 45 credits, 2 × 2, Performance −8%, Efficiency −5%. It is a cheap way to fill space, but it makes the machine worse. Do not install it in a machine you depend on.
Neural Core Module (Uncapped) — 1,500 credits, 2 × 2, Performance +200%, Quality +100%, Efficiency −100%. It is a critical-level contraband item sold by the Hypertech Smuggler. The performance gain is enormous, but the efficiency penalty is severe. Expect a major power problem and plan for it.
A capped version is reported at 250 credits, but its exact stats are not confirmed. Do not buy it assuming it matches the uncapped version.
Stacking and diminishing returns
Community reports describe module effects as additive, not multiplicative. Two +25% Performance modules are treated as +50%, not +56.25%. This is plausible but not officially documented; verify on your build before spending on a full set.
Even additive bonuses can hit caps. Efficiency has a minimum power draw of 1, so stacking efficiency beyond that point produces no further benefit. Performance may have a similar practical limit when the machine cycle is already shorter than the interaction time.
Best upgrade order
| Priority | Module | Why |
|---|---|---|
| 1 | Quality in chemistry | Purity tiers are price tiers |
| 2 | Efficiency in overnight machines | Power savings compound daily |
| 3 | Performance in bottleneck machines | Faster cycles only help if inputs keep up |
| 4 | Quality in hydroponics/genetics | 50% machine effect makes it efficient |
| 5 | Bay expansion | Fits more of the above |
| 6 | Corrupted module | Only for disposable machines |
Do not buy a Performance module for a machine that is already waiting on input. The bottleneck is the supply chain, not the machine speed.
Modules vs Workshop mods
This is the most common confusion in the game's search results:
- Machine modules are in-game parts installed in a machine's module bay. They affect that machine.
- Workshop mods are external files subscribed through Steam. They can change the game's rules, UI, or content.
A page about “Probably Stolen modules” can mean either. This wiki uses modules for the in-game parts and mods for Workshop content. The modules vs mods page explains the difference in detail.
FAQ
What do modules do in Probably Stolen? They modify a machine's Performance, Efficiency, or Quality. The effect depends on the machine.
How many modules can I install? It depends on the bay stage and the shape of each module. A standard bay has 35 cells, but only 26 are usable initially.
Are modules permanent? No. They can be removed with a Module Extractor, but the basic extractor has limited uses.
Is the Neural Core Module worth it? It gives huge Performance and Quality but −100% Efficiency. It is a specialist item for a machine with power to spare, not a general upgrade.
Community source: community module testing, in-game machine panels, and the Steam Community guide hub ↗. Store reference: Probably Stolen ↗. Workshop examples: Steam Workshop ↗.
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