You've gotta leave the bassett tee unless you use some kind of electronic water control(such as the Banderlog Water Injection Valve, details available at banderlog.com). It shuts the water off at idle. If you have water running to the header at low engine speeds, you take the chance of water entering the cylinders, which can cause major parts breakage.
You can use a valve to control the flow of water at speed, though. I have a ball valve before the tee, allowing me to choke the flow down or shut the water off if I want.
Hope this helps you out.