Atilla, I haven't seen a similar problem, as a matter of fact mine pitches slightly to the canopy in KE.

What you are describing, with it being good one way and pitching out the other, sounds like a function of thrust and fuselage shape. It's quite common for a plane to need some mix, and no matter how hard you try to get 2 to behave the same way, there are subtle differences, sometimes large differences.

A lot of things come into play with rudder coupling. Balance point, incidence, thrust, wing/stab shape and location, airfoil to some small extent, fuselage shape, weight....so it's a balance. If you've checked and seen that everything is straight, I'd first suggest some mix if your radio allows it. if not, You're going to have to try small changes, one at a time, until you find one that gives a good result.

There's nothing that can't be fixed or changed, sometimes it takes a while though. I'd love to hear what you come up with, because that's a new one on me.

-Mike