there is no tier 2, only tier 1…adding extenders adds CPU amount to your base/ship…single extender (any) adds fixed CPU amount to your available CPU amount
The CPU, power, mass, and volume of nearly every block and item has been rebalanced. CPU tiers no longer exist. Most non-functional blocks no longer cost CPU.
Each individual CPU extender increases your maximum CPU. You can have a full set of 1 Basic, 2 Improved, and 5 Advanced extenders at the same time. Crew adds a small bonus amount.
You can expand your CPU limit even further with difficult to obtain Quantum Extenders or Auxiliary Cores.
Building multiple ships specialized for a specific task or role that fit within your available CPU is now more important.