I assume that you are measuring the wing incidence at the side of the fuselage or wing center joint. But because of the washout in the wings, you must measure the wing incidence at the center of each wing panel, half way between the fuselage and the wingtip.

Washout increases stability when the airplane is right-side-up, but it decreases stability when inverted. That might explain the comments about inverted flight performance.

Also, the airfoil shape determines the necessary wing incidence. With the Kougar's fully symmetrical airfoil, the wing will have to have positive incidence in level flight. If the recommended setup is 0-0-0, it will fly with up elevator trim and be somewhat speed sensitive. Worse yet, add washout and a 0-0-0 set up at the wing saddle and you will need a lot of up elevator trim, which will make it very speed sensitive, which will then require a lot of down thrust to smooth it out.

It sounds like someone has taken a lot of time and trouble to try and trim your Kougar for completely neutral flight. Unfortunately, the Kougar was designed as a low wing trainer (per the Sig website) and you may never be able to get it there.

Jim