I dive my planes power off then give a hard pull up or pitch forward. Usually it will want to snap left or right one way or the other. I can trim using rudder trim to get rid of one or the other but not both. If I trim for reducing snaps when I pull up then the plane needs more right rudder in a hard climb. Trimming for an inverted pitch up, usually reduces the need for right rudder when climbing.
You should get close to neutral but I don't think you can eliminate all of it's tendencies to snap one way or the other.