In the custom race builder, if a player saves and loads a race they following are added each time:
+10% Social Production
+10% Military Production
+4% Logistics
In this way, a player can pump these up infinitely.
As a side note, what is the correct starting logistics value? I've made custom races, and I seem to start with a number between 4 and 6. This seems like a very important value to be assigned randomly?