Thank you for confirming the thrust angle.
I have a JC Cheetah in mine (yes, overpowered, but the engine is shared between this plane and a Krill Avanti S (FC) and under full throttle the Turbinator climbed at an alarming rate with the stock thrust angle. Granted, I don't really need full throttle...
I have ended up at about 15deg, but perhaps I should try a few more degrees of down thrust (I am trying to avoid any down elevator mix with throttle)

Did you measure the thrust angle with respect to the wing tubes? I am assuming that is the datum for this plane.