I'm wondering the same thing. I'm seeing a lot of contradictory info on the bosch sensor part number (aside from buying the rail complete with sensor and pressure relief valve). Some guys saying 0261545053 is what is needed, and others saying 0261545038 provides the correct pressure, yet others...
Quick vid of my test (had to cut it down for file size sake). Just keeps dropping after, no increase. I'm going to replace the FPV, just looking for general concensus first, please.
(Current background: Timing job just done - chain and the usual, friend helped me out. Whole kit from corksport...