I have discovered an extremely easy mod to increase the flow through a ball valve. Drill the hole in the valve larger. I have only tested this on my Vindicator's valve, which can handle at least a 1/4" hole. The Vindicator has been in pieces, and I lost most of them, so I cannot range test for improvements. The valve still seals perfectly, as far as I can tell.
If you have a Vindicator or Vanquisher, this might be a pretty good idea.