Do you have to buy this kit they offer for the SFMU to work with the same lines that the regular FMU uses, or are these fittings you could buy at a hardware store if you needed to? what did you guys use?

www.TeamKLR.com
1997 Silver RS
Wiseco 10.5 Pistons
Eagle Rods
T3/T4 Turbo
Custom FMIC
Greddy Exhaust
440's

well the fmu works with hose barbs. the sfmu has -6An fittings instead to use with s/s fuel lines for example.
the kit is basically a set of reducers, but they are all I believe npt thread.
i believe with that kit you will be able to attach the barb for the return line (if you with to go that way) but you will still need to buy some -6an to -4an reducer to attach the sfmu to the fuel rail.

I made a write up on how to set up the sfmu and teh fuel return line.. check it out is in the mods section on the main site.

hope that helps.