Parts bigger than 10m would be fun. However, I think the biggest challenge to large parts is the size of the VAB. I have hanger extender mod and it is still quite difficult to work with large rockets. Mr. NecroBones, I'm having a blast launching massive things into orbit thanks to your mods. Great work. My latest launch made possible with SpaceY Expanded: The orange tank is 16m procedural parts tank, and I use engine cluster of 12 Emus.