[garyt]

right did some searching through the piles o stuff I have on the mx5 and derivatives;
firstly;
" some have fuel return and these have regulator on end of fuel rail with a vac feed to inlet manifold which raises and loweres fuel pressure according to engine vac/pressue etc, this is system fitted to my jdm 1998 mk2 1.8, but apparently some other mk2 and mk2.5 have a returnless fuel system and on these fuel reg is in the tank and fuel pressure is static."

and secondly I think this is what you have as in diagram,

therefore pipe from fuel rail = fuel in, pipe from fuel pressure regulater (round thing) = RETURN line, smaller pipe from FPR (round thing) vac from inlet manifold

this would indeed agree with 2 x 8mm pipes and a smaller vac pipe, and so if this is what you have then 2 fuel pipes required front to back
hope this helps, good luck