 The F4 Tamburini was a special edition of the F4 1000 S released in 2005.It was the first F4 to be equipped with the Torque Shift System (TSS), which varies the length of the intake trumpets with speed in order to provide optimum torque at low and high engine speeds.Engine output was a claimed 173 bhp (127 kW) at 11,750 rpm and claimed top speed was .