A process of twinning a pair of polymer-insulated conductors to form a twisted pair, where the polymer-insulated conductors are formed by extruding a uniformly thick coating of polymer onto the conductors. More than one twisted pair is encased in a polymer jacket forming a cable. The twisted pair obtains a desirable average impedance performance using a reduced amount by weight of polymer forming said polymer-insulated conductors by: (i) extruding to form longitudinally running peaks and valleys in the exterior surface of each of the polymer-insulated conductors of the pair of polymer-insulated conductors and (ii) twinning resultant polymer-insulated conductors to nest at least one of the peaks in the exterior surface of one of the polymer-insulated conductors in at least one of said valleys in the exterior surface of the other of the polymer-insulated conductors of the pair of polymer-insulated conductors.