my vr6 turbo friend is a douchebag and has an fmu. i don't know how to hook that crap up. it seems to be right. Paxton fmu. fuel return line goes in then out another port. a vacuum line goes into the top then. we played with an adjustable regulator that we're not even sure who makes it which didn't work. now we have both the adjustable reg. on to raise the idle pressure then the fmu after it to raise it for boost. the thing also has an eip chip that's just a basemap since there is no free software for vw's.

 

The fuel return should be routed through it like you said and the vac line is connected up top.