evaluating a conversion capability of the catalytic converter volume on {HEAD ~ the basis} of a value which is a function of the first difference, the value being normalized to a value which is a function of {TAIL ~ the second difference} 
evaluating a conversion capability of the catalytic converter volume on { HEAD ~ the basis } of a value which is a function of the first difference , the value being normalized to a value which is a function of { TAIL ~ the second difference }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL