The pressure regulator isn't a simple on/off device - the TCM tells it how far to open/close depending on operating conditions. If you want to do it at the tappings, details will be in Bentleys. The consequences of getting it wrong? Too much and you could blow the clutch drum. (Its not the D/G as I mentioned above - that's on a 5HP18 - it will be the F but it goes for the same reason) Too little and there is not enough to apply the clutches. BTW, they did come out with a modified pressure relief valve for the 5HP30. It has a larger shoulder than the original and may be worth a look.