Hey all,
Having a strange problem with my MVVS 26 gasser, I have a WT540 carb, and a bisson muffler on it. I have fitted a static line to the carb back into the fuse which helped significantly with some inconsistencies I had.
The problem I am having now is whenever I put in rudder input, the engine sags considerably, release the rudder and the power picks up. Any ideas?

The problem you encounter now, is that the fuselage inside pressure is by no means constant, and changes when you apply rudder (Yaw the plane)
Connect the static line to a static tube ( http://prme.nl/forum/viewtopic.php?t=205 ), and your problem should be solved.