Hi Bill: Because boost tabs move in the opposite direction from the rest of the aileron, they will slightly reduce aileron authority for a given amount of aileron deflection. Boost tabs, however, greatly assist the servo in moving the control surface to the desired deflection, and the additional travel that they will produce beyond where the servo would otherwise be stalled can give several times the control surface authority. If the servo is able to move the control surface to full travel, unassisted by boost tabs, there is little reason to use boost tabs. I like to use boost tabs on models with largish control surfaces simply to permit the use of lighter weight and less costly servos and smaller battery packs.