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Upgrades can be purchased at most shipyards, and come in M, L, XL and XXL versions (so a S station can be upgraded to M using its upgrade; a M station -> L etc). Stations can only be upgraded sequentially, one tier at a time. The time taken to gather production optimisation information increases with each tier, meaning that it will take longer to unlock the ability to upgrade further. Upgrades can be applied to stations even if they are part of a complex, allowing compact, high-production complexes to be created.
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