This has come up a couple of times, some say one thing others say something else. E.g. left valve feeds 2nd dv and d/s right feeds Primary dv and wing. Some say the opposite i.e. left feed 2dv and wing, rh feed primary dv and d/s.
Have a look at this thread which will also take you to Dom's site, he is quite keen I believe on the DIR view, although he would be the first to say he's not DIR. You may also be influenced by which hoses fit, unless yo go to custom lengths.
HTH
Matt
Twin setup.