an outer cylinder depending from the insulation cap and at least partially surrounding the inner cylinder to define an annular exhaust gap for {HEAD ~ exhaust gas} from {TAIL ~ the exhaust plenum} 
from
an outer cylinder depending from the insulation cap and at least partially surrounding the inner cylinder to define an annular exhaust gap for { HEAD ~ exhaust gas } from { TAIL ~ the exhaust plenum }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL