correct and correct. i actually forgot about the returnless style duel systems that use a FPR that isn't vacuum referenced. i know some LSx cars are like that and for applications i'm used to, the 3500 and 3900 V6 units are actually similar, they have an in-tank pump/regulator combo with no vacuum reference. pretty sure that they don't use a PWM fuel pump either....
and it's pretty easy to allow the ECM to know that you're removing the vacuum reference to lower fuel pressure, just modify the VE table at the various MAP points.
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