Alright i have been trying to figure this out, I was told that having the same size feed and return is not a good idea. A few questions.
1) If I go with a -6 AN feed, should I go with a -4 AN return?
2) From the test port to the S-FMU is this part of the "return" portion, or feed?
3) What size lines should connect the S-FMU to the test port? -4 AN? Will -6 AN be a problem?
4) Can I run -6 AN all the way? or keep a -6 AN feed, and -4 return from the test port back?

Work in progress
98 GS t3/t04e, hrc Sidemount, tial 38mm, HKS ssq bov, clutchmaster stage 4, wiseco pistons, Eagle rods, Apexi TT, HKS EVC II, Phantom grip lsd, 3in turbo back, Eibach pro-kit, Defi D-gauge EGT,boost, autometer fuel pressure
8-inj setup in the works, HKS AIC III and 450cc injectors