5600gr is to heavy for the 120..maybe its the pipe but im about 5700 with the 160 gas ant pipe.Engine with the accesories is 1450gr so maybe one of as has bad scale.
I think i can save some weight by changing tha throtle servo to a smaler one and maybe can take some balsa off the canopy conpartment...But the best end more expensive is to change the wing tube and landing gear with carbon ,and the engine base with a plastik one
I estimate one can save about 300-350gr this way ...