Supercharger folks, come see

[mike72678]

you put a vaccum line to that port on the bypass valve , the vaccum will hold the bypass valve open and when the vaccum turns to boost , the boost pressure will in turn close the bypass valve so the air can no longer recirculate . If you want to know that info about the fmu , you are going to have to call the manufacturer , however they will probably reccomend not to use the fmu as well .