Just finished quickly reading through this thread.
When using a linear 5 bar fuel pressure regulator "fpr" with a boost port (i.e. Bosch), the fuel pressure will be 5 bar plus your boost pressure. So it could be even 6 bar or higher. The OEM fuel lines are not suitable for that and can slip out and then you crash and burn. So better fit high pressure fuel lines and fittings. By the way, you must connect the fpr boost port to the underside of the throttle bodies in order to reduce fuel pressure under 5 bar during idle or partial load, this will help to tune it a lot.
Have any proof of this besides opinion? I say this as I have been running this configuration for quite some time (and yes using the oem vac port on the throttle body itself as a reference) with zero issues. I know Richard (TTS) has been selling this option for a few years as well and haven't heard of a single fuel line failure.
Please let us know IF you had this issue (or have data) as I certainly am concerned. FYI: This would be the first time I've ever seen an oem fuel line have such issues on any platform. I've gone way beyond stock pressure on almost every vehicle I've raced/tweaked over the years (and that includes some serious 80's garbage) and never had an issue. Not doubting you, but I'm not in belief unless you have some data or experience.
More stuff:
Jan, heven't seen you post in ages.
Wanted to let you know I fixed the Delphi baro issue by creating a circuit to modify the 2 bar MAP sensor voltage to the correct 1 bar map sensor voltage (what the ECU expects) when under 1500 RPM. The ECU is only sampling at that level (and key on engine off as a baseline, which I cover as well). Cost me a total of $8.00 and some time with my Fluke to get it nailed down. The hardest part was ignoring the misinformation regarding how it works that certain people told me about.