This disclosure relates to a high performance electrical connector, such as a modular plug, for example, used in high frequency data transmission systems, where such connector is intended to be mated to a receptacle type connector. The modular plug comprises a dielectric housing having a conductor receiving end, a conductor terminating end, a passageway communicating internally between the respective ends, and a spacing or insert in the passageway to receive and/or separate a plurality of conductors and to position them in a manner to improve the crosstalk performance of the modular plug. A preferred insert is characterized by having an upper surface and a lower surface to space or separate selected pairs of the conductors. Within the limits of the housing, the insert or spacing maximizes the separation of the selected pairs and arranges them in plural planes before being realigned into a common plane for termination at the conductor terminating end. Several alternative embodiments for the insert are disclosed, ranging from solid bodies to spacing members which may be removable.