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