Quilidity
I know space travel in ME is done threw relays but couldn't the fallout scientists create travel using sub/hyper space thus giving them a serious advantage.
ME ships can actually go faster than light. It lets them travel in and between local solar systems relatively easily. Travel via Mass Relays is near-instant. Being able to go 10,000 to 100,000 light-years that fast is basically galaxy-spanning teleportation. I can't think of anything besides maybe Star Trek, Doctor Who, or War Hammer that could beat that. If you're just talking about speed increases for dog-fighting then I think there is a limit on how much speed is usable. Most Sci-fi series I know "drop out of" light speed before they start fighting.