The CHECK TEE incorporates a pressure-activated check valve. No longer does one need a post-IC nozzle holder with check valve built-in. Nor is an inline valve needed. Compact holders can be safely used without any fear of gravity siphoning. The modular design also allows use of compression fittings or -AN fittings for no-drip security. This part attaches directly to the feed end of a flow control solenoid.
Most importantly, this configuration allows for independent triggering of main air cooling and then octane spraying. Intake air temperature reduction becomes meaningful early in the boost range. -about 5psi+. Whereas, the need for extra octane coincides with medium to high manifold pressure. Smart builders incorporate a boost switch to open a solenoid just before timing pull is experienced.
This way, when the pump is activated by the controller, fluid hits the shut solenoid and diverts out the side of the t-fitting to go down to the air-cooling position only. At the right boost pressure, the solenoid is commended open and octane protection is provided when needed.
Triggering all nozzles at the same time often quenches combustion down low. Torque suffers. So, then the spraying is delayed until a higher load. It works, but then there are NO COOLING benefits down low. With a CHECK TEE and supporting bits, you can do it right! -more gains more of the time and easier/smoother tuning, too.