As far as i know, you can't actually make a system bigger. What you can do is increase the nav map scale, which is the zoom amount on the nav map.

1 is normal level - Manhattan
>1 is smaller then normal
<1 is bigger then normal

Look in universe.ini

There also tutorials for how to make planets and stars bigger in the Tutorials forum while objects like stations could have their size increased with the use of FLModelTool (just remember to stretch the sur file to cover).

Freeworlds Mod Developer
Author of Modular Station

'There is no Good nor Evil in the universe, just perceptions and circumstances.'