If you're not using water injection remove the fitting and put a plug in the hole. You don't want that open and exposed to the engine bay.
Fast Fairlane said to tee the line from the belly of the pipe to the stinger. I'm not certain but I think that may be a mistake. Mist dry pipes have three fittings in the water jacket, one right by the connection to the manifold, one in the belly of the pipe, and one down by the stinger. The one down by the stinger is not to be confused with the fitting for the water injection INTO the stinger.
Typically dry pipes are set up so the water goes into the jacket by the manifold, out by the stinger, then the fitting in the middle of the belly of the pipe is connected to the stinger water injection with a restrictor or flow control valve or both.
Personal opinion I would restrict the flow going into the stinger with about a 1-1.5mm restrictor, basically find the size that has the waterbox at about 170 degrees or so. I've done this personally on wet pipes, but not dry pipes, so your mileage may vary. Some people restrict the flow INTO (not out off) the water jacket to get the temp of that up also. That's getting into territory that I have not personally tried though, so take it for what it's worth.
The above description leaves you with at least two water overboard lines. Probably, you want more water going through the motor itself than through the pipe chamber. Not sure. Possibly you could run it all through the pipe chamber or possibly you could t them back together for one large overboard fitting. If it was me I'd be willing to try that, I'd use the biggest least restrictive overboard fitting I could find and I'd keep a very close eye on temperatures. I have not tried, and it is not the conventional way to do this, so you would be in uncharted territory.
