*:\Program Files (x86)\Steam\SteamApps\common\Starpoint Gemini 2\Spg2\Models\Ships (*= where you installed the Steam library)
In the "Ships" folder find the ship folder you want to change open the .shp file using Notepad, when opened look for "Cargo" and increase as you want
There's plenty of stuff to play with as: Value, Hull, Crew, Hangar, Cloak....
But be careful, some values cannot exceed a certain amount without crashing the game (memorable experiences...)
Sorry for the late reply
[Edited by B4Marc, 11/9/2015 4:13:58 AM]