Use of twin screw extrusion to further enhance the uniformity of crosslinked rubber dispersion in thermoplastic vulcanizates (TPVs) to improve elastic properties of TPVs is disclosed. Most specifically, this invention employs intermeshing twin screw extruders to further homogenize dynamically vulcanized rubber dispersions in TPVs so that their particle size dispersion index (PSDI), or the ratio of weight average equivalent dispersion particle diameter to number average equivalent dispersion particle diameter, can be lowered to less than 1.6 or 1.57 with corresponding elastic property improvements by having lower hysteresis, higher elongation to break, and higher retractive force. TPV products having lower PSDI and improved elastic properties, and apparatus for conducting the disclosed method, are also provided.