Is the bow for "RUle of Cool" or "Realism?"
Realistically, why use a bow when you can use a gun?
If it's because a bow is cool, I would have a powered bow of some kind that has a kinetic draw that when pulled requires next to no strength, but when a charge is sent through the "String" is whips itself into heavy pull like a muscle, not relying on pulleys and tension, but electric pulses themselves.
Essentially it'd just up the bow strength by whatever margin. I'm inclined to add whatever I had to in order to make it effective for the campaign.
You can also have Superfine arrows of course, which would give +2 damage and armor divisor. Maybe some other technology could be employed to improve this, like hyper dense arrow heads with carbon shafts.
Heck, you could even do blaster arrows. They certainly did this in Star Wars Clone Wars.
http://a.dilcdn.com/bl/wp-content/up...Lineup-TCW.jpg
Notice the strings themselves are energy and not strings?