Command & Control Block
In PvP we need some kind of block that will put limits on how large a ship we can build. This block need to limit the number of thruster, turrets, reactor, fixed weapons, gyroscopes, jump drives etc... that can be placed on a ship. But this block also need to be expandable, so for example a basic Command & Control block will handle 2 turrets, if I want more I have to buy a fire control module which will expand my turrets count by 2 , allow me 4 turrets. Another module could be structural integrity, a basic C&C Block might only allow you to build a 100 block ship, what more blocks you need a structural integrity module.
I feel adding either a block or system that requires player to pay resources for upgrade and extra capabilities would greatly help multiplayer.