Huh? I've had many of my bikes with the FD cable running along the down or top tube that slapped the tube from hitting bumps. And I'm sure you have as well. Why would you post such a thing?

T.dub, the cable tension in the FD is what it is. The tension is set by the return spring in the FD. When you make it tighter it moves the FD and shifts. So you can't make it any tighter than it is already assuming that it is shifting correctly at present.