The pipe that curls back on itself is the INPUT, the regulator is at the END of the rail, so as to cause the pressure to exist in the rail, by restricting it's flowing out, backing the pressure up sort of thing.
The pipe is indeed a shrunk fit, if removed these can be simply replaced with flexible pipe, the pressure is not extreme, when I test rail pressure I don't even need to put a jubilee clip on the pipe from the end of the rail(2wd), the hose is a tight fit and no leaks.
Had a few leaks today mind on a 500bhp 3 door, getting ready for mapping session, brand new engine started 1 st turn once fuel was through, running mega rich though, running GT series with side exit pipes screamer pipe etc!!
tabetha