Board Thread:Warhammer 40k General Discussion/@comment-24.177.35.35-20130913034201/@comment-3580035-20130913103334

It has been stated that during their Second Sphere Expansion, they developed the ZFR Horizon engine that allowed them to go to near-light speeds. During the Third Sphere Expansion, they were able to reach "hitherto unthinkable velocities" with newly developed impulse reactors, implying FTL.

I have yet to get the second edition of the Taros Campaign book though to see whether or not they kept the Ether Drive info.