A lead extension at least one lead extension body terminals disposed along one end portion of the lead extension body(ies) a lead extension connector disposed along another end portion of the lead extension body(ies) and conductors electrically coupling the connector contacts in the lead extension connector to the terminals. The lead extension connector can include lead channels with non-straight paths to facilitate retention of leads. Alternatively, the lead extension connector can include one or more stretchable boots to each receive a lead when stretched and to grip the lead when relaxed. Alternatively, the lead extension connector can have two connector bodies with a pin channel and pin, respectively. When the pin is inserted into the pin channel, the pin compresses a portion of the connector body against the lead to retain the lead within the connector.