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Message: [QUOTE="H&S Bentley, post: 795217, member: 627"] Didn't read this entire thread, so not sure if it was answered. BUT, here is what we found. The OEM low pressure system has a pressure switch that triggers anything under 50PSI. There is a pretty high debounce on the system though, so it takes anywhere from 10-30 seconds of maintained low pressure (under 50 psi) before any dash messages are triggered. The system is not integrated into the ECM, but rather just sent to the instrument cluster to warn you of "low fuel pressure" (I am pretty confident on this, but not 100%. I cannot find any data in the ECM for low pressure fuel system trigger switches). If you unplug that low pressure switch the system is happy and will not report any dash messages. It is a normally open contact and stays open on unplug. We ran a low pressure system gauge on my truck for a few months, and I could not ever get it to fall below 15psi, even on some VERY large duration tunes. Thus far we have seen no negative effects of running less than 50psi pressure to the CP4. We can also verify that the LML duramax (with essentially the same identical fuel system) also does not have issues running low lift pump (built onto the CP4 pump of the LML) pressures. H&S Motorsports is currently doing more testing on low pressure system upgrades to see where they are going to be necessary, and to find what exactly should be replaced. So far it looks like the 50PSI idea was a Ford thing, and not really necessary for the Bosch fuel system, it will run at much lower pressures and still be 100% happy. [/QUOTE]