Depending on the cuff length and shape, the leading-edge cuff can exert an aerodynamic penalty for the stall/spin resistance speed obtained, resulting in some loss of cruise airspeed, although sometimes too small "to be detected with production instruments".[20] In the case of the best wing modification of the AA-1 Yankee, the loss of cruise speed amounted to 2 mph or 2% and there was no speed loss in climb.[21] Impact on cruise speed of the Piper PA-28 RX (modified T-tail) was not measurable.[22] For the Questair Venture, "In carefully controlled performance tests, the penalty in cruise performance was found to be imperceptible (1 kt)".[23]