It's gyroscopic reaction from the propeller... all planes snap better to the right because the gyroscopic reaction during the yaw to the right keeps the nose from pitching up too much and burying the snap. In a snap to the left the gyroscopic reaction causes the nose to pitch up even more and the snaps tend to be slow and mushy... the solution is either to use less back stick when snapping left, or after you begin the snap unload the backstick all the way to neutral or even foreward slightly.

Ty