Here is a Diagram For a Stage One Turbo Setup.
...........When running the vacuum lines you need to add two check valves before the map sensor to bleed off the pressure before it hits the map sensor. The boost leak is very small and wont effect the overall pressure.......
The optional routing is used on the 05+ 1000 as it has two sets of injectors so its harder to plum in another fitting.
I think the fuel-T main channel must be quite restrictive to make this work w/o affecting the actual boost reading and boost. If not, the boost gauge would see the same reduced boost as the MAP sensor. Better to reduce the signal with a simple electronic circuit IMO.