This is huge! Great work dardagnan!
I believe splattttt had a reg'ed phantom working at 450 to 550psi (he ultimately found that although it was capable of being run as low as 450psi, it was more consistent within the higher end of the pressure range, iirc).
After much brainstorming/theorizing/testing (see Nelson Valve Evolution (Project Leprechaun), in custom projects forum) many have come to the conclusion that modifications to the powertube and valve are necessary to further the lower pressure threshold of nelson feasibility. Some have mentioned the possibility of increasing valve volume by using an RTR valve body.
You may have re-emphasized the importance of increased valve space.
dardagnan: Did you alter your powertube, or are you using a stock CCI powertube? open faced or three ported TPC? Oh, and thank you: I can now put my French-Linguist-grad-student-girlfriend to work translating for me! No problem with your english here! keep your posts coming. thank you for your contribution.