Boost issue after installing new MBC

[Breitling]

Well,

I just installed a new Grimmspeed Manual boost controller on my s14 240sx (Redtop SR20)

Backstory; Prior to tonight i had removed the old hallman MBC in efforts to trace down a Fuel pressure issue. Fixed the fuel pressure issue while the internal T28 wastegate was linked directly to the 50mm tial BOV and it was getting a dead-nuts factory 8 PSI (factory waste gate setting)

Tonight I put the new MBC inline and loosen it so that the boost controller is all the way "undone" and now the car is boosting to like 20 LBS of boost when i test drove it. my thought is that with the boost controller all the way loosened i should be right at 8psi... no?


Things i noticed.....

the vac line going from the wastegate to the MBC is "split" into one of the vac fittings on the intake throttle body..... could this be the problem? if so. how come it didn't affect it with just the wastegate & 8psi scenario.

HELP