I think the problem lies in the changes from the FX to the AX. There is plenty of 'cheek' cut away from the plane, and I'd have to remove some of the structural support in the corner of the engine compartment to make this thing fit (due mostly to the squared-off corner of the muffler).

I'm wondering if there is a gasket that can go between the muffler and the engine to give me 1/16" or something.