Selective laser sintering is quite advantageous to build complicated tubular structures such as intake manifolds of automotive engines because of its ability of building undercut structures without using support ribs. On the other hands, inevitable opacity of the parts obtained from the process is lowering its advantage when we need to observe inside of the parts. A technology that can transparentize SLS processed parts by infiltrating curable resin with tuned refractive index was introduced by the authors in 2004, and in this paper, several modifications are added on material, process parameters and their control accuracies to improve clarity of obtained parts. As a result of these modifications, haze of the processed part was reduced by a factor of 40% reaching the lowest value of 20% through a plate with thickness of 5mm.