not much point, unless you are having mapping wok done
they are adjustable yes but are not smooth/progesive
i used an adjustable and boost sensative fuel pres reg on my 20v rallye but it was on mbe management and i could map it so it was brilliant
i used it on a big power r5 turbo when i used to do dyno/mapping work , to get more fuel accross the whole range
and it worked well,
i cant really see it being usefull on a g40, only benefit would be if used in conjuction with a specific injector size and mapping session,say for example to use an injector slightly smaller than g60 (to enable fine tuning at idle as g60 injectors are a little hard to map at idle) and run a slightly higher fuel pressure,
people have probably been "recomended" to use one if you had a power run and it was starting to lean off further upthe rev range, where really you need a bigger /new fuel pump to keep up with demand or fuel pump is on the way out, or the car needs mapping
maybe worth trying one, with a guage! and setting it to factory pressure 3bar?
?? maybe
also running wide band and then monitoring afr whilst turning it up say0.2 bar increments.....
