The system 1, wherein a ratio of plugged area to {HEAD ~ the total cell area} of {TAIL ~ the flow through honeycomb substrate} is less than 45% 
The system 1 , wherein a ratio of plugged area to { HEAD ~ the total cell area } of { TAIL ~ the flow through honeycomb substrate } is less than 45 %
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH