Wastegates on the 7.3
KC does not advertise their spring pressure for two reasons. First is most people don't understand how it even works and will misinterpret what it means. Second is people tend to literally copy our specs, so keeping some information secret helps slow down this process.
Boost does not open the wastegate. Even with the red hose hooked up... although it "can" blow open the gate depending on the tuning/pcm strategy. Watch this video to better understand the red hose
Ok so what does open the wastegate? EBP pressure against the wastegate flapper on the inside of the turbine housing.
Ok so why not just give the spring pressure? That is because the spring pressure is not an exact correlation to when the gate opens. A 10 psi spring will not "open and 10psi of boost". It will also not open at 10psi of EBP. You have to take into account the surface area of the wastegate flapper + ebp psi + spring pressure. Even with all the info the gate does not just "open". It slows opens as psi increases it will slowly open the gate more and more. Adjusting the "preload" will only adjust when the wastegate cracks open. It will still be fully open based on the spring pressure.
Wastegates can also be used for a lot of different reasons, for example on an ecoboost gasser truck it is crucial not to make too much boost too soon because AFR ratios need to be exact. Even at low throttle and low boost (2-3psi) the PCM might be blowing the gate open to keep boost low and AFR where they want without having to close the throttle plate too much. Diesel are completely different. No throttle plate on most models, AFR ratios are very forgiving, and typically you want as much boost as soon as possible and setups like a 7.3 the gate is simply used to "prevent or limit max boost/ebp".
Wastegates can also be used for a lot of different reasons, for example on an ecoboost gasser truck it is crucial not to make too much boost too soon because AFR ratios need to be exact. Even at low throttle and low boost (2-3psi) the PCM might be blowing the gate open to keep boost low and AFR where they want without having to close the throttle plate too much. Diesel are completely different. No throttle plate on most models, AFR ratios are very forgiving, and typically you want as much boost as soon as possible and setups like a 7.3 the gate is simply used to "prevent or limit max boost/ebp".
KC did a lot of research when picking and sizing the gates. Feel free to adjust as needed... but unless you are having issues I would not worry about it.