By using a relay, you could use it to trigger a pump. The MSD RPM switches are designed as a low amperage switch. If you use it to trigger a relay, then you could use the higher amperage out the other side of the relay to run the pump or solenoid, as you prefer. Seems triggering a solenoid and having the pump allready running would be quicker, though. How about just incorporating a second spray bar in your existing plate with separate and tunable nozzles??????