Talk:Loki (Warframe)/@comment-79.81.232.127-20131003031403/@comment-65.13.130.53-20131004102400

This is taken directly from the Vitality page:

The increase is applied to the base (rank 0) health of the Warframe, before health from  leveling  is taken into account.

This basically means that it is adding the 200% to your 75 BASE health, not the level 30 health. A rank 4 will cap out on a Loki at 375.