The exhaust control system includes {TAIL ~ an exhaust control valve}, and a primary and a secondary exhaust purifying system located downstream of {HEAD ~ the exhaust control valve} 
The exhaust control system includes { TAIL ~ an exhaust control valve } , and a primary and a secondary exhaust purifying system located downstream of { HEAD ~ the exhaust control valve }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD