Just installed the new AMD 14.6 driver for a modest 10-15% boost on X11(darkcoin) without changing anything else at all.
Some people were reporting up to 80% more Hash on some cards depending on the algorithm so I thought I'd give it a try!!!
Seems you can tweak setting a little more as well, so I may be able to improve more with some other tweaking.
Warning: Keep an eye on your temperatures while tweaking with this driver!
This might muck up your graphs a little

I am on 14.4 and 13.12 depending on what rig, but I have heard EXACTLY the opposite.
I have heard 14.6 gives 10-15% lower hashrates, and people are going back to previous
versions. You may have just got higher hashrates because you did a proper clean uninstall
and re-install.