I throw about 25kms, but that's come from refining the shot for about 3 months....
The general rule is: the harder you try to throw it, the slower the shot will be.
Your ball speed will come, not from trying to throw it hard, but from finding the hit spot in your swing. The cleaner it comes off your fingers, the faster the ball will roll, because the momentum of the ball will create the speed.
Are you close to Village? I might go there this weekend sometime....either that or Salisbury....