Max allowed pressure before venting is 1.4 bar as opposed to 2.0 bar. It does not lower the normal operating pressure of the system. Just the max pressure before venting as the expansion tank cap acts as a safety valve. I will be putting one in soon myself.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards