I would say the first version of the Mass Relays could be just an external oversized drive that throws the ship across interstellar distances. Because the drive has not to move itself, the "drive to mass" ratio becomes more than one, which could allow a higher speed.
But I am not really "planning" Mass Effect Relays" at the moment, they are still a distant dream I would like to do. ^^
But I am not really "planning" Mass Effect Relays" at the moment, they are still a distant dream I would like to do. ^^