HI this could help you out.
I had some big problems with my whammy after pull downs and pull ups.
IT wouldn't come back in zero position and in tune.
I tried blue steel, fender, GHS, D'addario etc strings, nothing helped.
First i tried 09-42 all brands. Then i tried 010-46 all brand.. still not in tune after whammy abuse. Far away from in tune.
Then i tried D'Addario 010-52... wow now i can abuse the whammy the whole day and it still in tune at night.
So for me i fixed my whammy problem by trying D'Addario 010-052.
If you have problems with a whammy that wont stay in tune try the 010-052.
It could help you.. its worth trying. OOHH you need 4 springs i think.
Sorry for my bad english... Hope you understand what i wrote.
All the best guys.