Is here any new tech in the Laboratory after 30 level?

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Looking for some top players, they have a lot of troop, but not more attack and defence than me.
Is here hidden ways to up a troop maximum, or it is simple general 50-55 level + ~40-45 level of Accessory?

My Naoe Kagetsuna have 45 level and Legendary Book of Han (up to 40 lvl). HP = 2886.
+10 levels (up to 55) = +300 HP.
And I can change Book of Haan on Zen Flute, for example. This will give me extra ~900 HP, but will cost over 13 million gold (approximately).

I think, this is expensive (moreover, for 5 generals), and i doubt in this version.
Dont want to waste a several days for a bad experiment...

Does anyone have helpful information?