Installing Manual Boost controller

[Coronet500]

I decided to turn up the boost on my 91 Shadow ES. I bought a Manual Boost control that has a ball and spring in it. I was going to to instal it between the waste gate can and the nipple coming of the compressor housing but there is another vac. hose T'd in there that runs up to the fuel rail area. I'm not sure what that hose is for and what should I do with it?

[Moparbishi]

is it running to the fuel pressure regulator.?
if so then leave that hose there so your regulator reads the vacum straight from the turbo to know how much fuel to push.
run the MB before the tee.