First thing I have to say: Check valve my ***!!! The problem with running boost with SD is that your MAP sensor will only read vaccum, and maybe some boost tp a certain extent. The solutions I've read on different boards was to put a check valve on a T before the MAP. The problem I encountered with that is that check valves in these sizes will not flow enough. I've tryed many!
But my engine kept cutting off at 3000 rpm.. Not fun!
What works:
What I did, on top of a small check valve before the MAP, I put a solenoid valve to block the excess boost going to the MAP that the check valve was not able to bypass. This Solenoid, wich is normally open closes at 2-3 psi with a pressure switch I'm using also for my water injection system. Problem solved! The best route is to go MAF. I just don't have the money at this time.
Costs:
Check valve(metal pcv valve): 3$
pressure switch: 19$
Feel free to ask any question,
Nik
PIC: CHECK VALVE ON A TEE. TUBE GOING INTO SOLENOID THEN MAP.