Unusually for a fighter of this time, the exhaust was muffled by the turbo-superchargers, making the P-38's operation relatively quiet. The two turbo-superchargers also provided the P-38 with good high-altitude performance, making it one of the earliest Allied fighters capable of performing well at high altitudes. It was extremely forgiving and could be mishandled in many ways, but the rate of roll in the early versions was too low for it to excel as a dogfighter. The P-38 was the only American fighter aircraft in large-scale production throughout American involvement in the war, from Pearl Harbor to Victory over Japan Day. At the end of the war, orders for 1,887 more were cancelled.