i want to keep using the fmu and all that

But how does your map not see bost with the vafc (i have one already)

 

If you use larger injectors(like DSM 450s) with an AFC, you have to set the AFC to -40% fuel trim in order to idle and run them. With the AFC set at -40%, it cuts the MAP signal by 40%, allowing you to boost up to 10-12lbs without throwing a MAP CEL.