A comb-like insert having a body and plurality of tapered fingers is installed with its fingers disposed within respective minichannels. The fingers and their respective minichannels are so sized as to restrict the channels and frictionally hold the insert in place in one dimension while providing for gaps in another dimension such that the flow of refrigerant is somewhat obstructed but allowed to pass through the gaps between the insert fingers and the minichannel walls and then expand as it passes along the tapered fingers to thereby provide a more homogenous mixture to the individual minichannels. A provision is also made to hold the insert in its installed position by way of internal structure within the inlet manifold. In one embodiment, an internal plate is provided for that purpose, and the plate has openings formed therein for the equalization of pressure on either side thereof.