{TAIL ~ The intake and exhaust control systems} are operable in {HEAD ~ varying modes}, according to the engine speed, by a single actuator 
{ TAIL ~ The intake and exhaust control systems } are operable in { HEAD ~ varying modes } , according to the engine speed , by a single actuator
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH