We have confirmed that the presence of water adversely affects {HEAD ~ the ability} of suitable HC trap materials to {TAIL ~ adsorb HCs}, with the consequence that the overall performance of the system in dealing with emissions during cold start, or before light off, is reduced 
to
We have confirmed that the presence of water adversely affects { HEAD ~ the ability } of suitable HC trap materials to { TAIL ~ adsorb HCs } , with the consequence that the overall performance of the system in dealing with emissions during cold start , or before light off , is reduced
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL 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