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