In the case of headers, that ball valve should only be in the line leading to the primary tube injection lines and act as a backup to the Bassett valve.  It would be plumbed off of a tee in the main water line between the jet pump and the gate valve or pressure reducing valve (whichever you prefer) and before the Bassett tee valve.  I like to install the Bassett valve as close to the primary tube injection lines as possible to reduce the volume in the lines that will retain pressure.  The nozzles in the primary tubes should not have an opening larger than .028" or or you will get too much water injected very close to the exhaust valve.  I also feel that the water doesn't atomize properly, instead will enter the header tube as a stream (or dribble).  You would see water dripping from the weap holes if this is not right.

During operation, the ball valve would be closed at idle and opened once on plane then closed just before you come back to idle.  Be advised that these injection lines will continue to flow after the ball valve is closed until pressure in the lines equalizes.

The water being injected into the through-transom collectors should be continuous flow to prevent the exhaust hoses from burning.  Some feel that wet exhaust robs horsepower.  It is possible to reduce the flow to the collectors by adding a through-hull dump to bypass some of the water.  IMHO, I don't feel that that is worth the risk.

Good luck,

Joe

When you run one of those smaller valves what kind of line do you run to and from it to keep it adjustable?

So you said it's a back up to the Bassett tee valve does that mean I don't really need to worry about putting it in or is it still a necessary piece of equipment with this set up?