I recommend aem fic do not use safc I am not familiar with blox but if it just intercepts maf signal like safc it most likely will not work correctly. I am surprised your car is even driveable with 440's and no engine management. That fmu will work also but you will be limited in boost to about 10-12 psi max

 

FMU is a mechanical device, not an electronic device. it's like a secondary fuel pressure regulator.



i'm still beside myself that with no fuel tuning or adjustable fuel pressure regulator and stock MAP/MAF, you installed 440cc injectors and the car ran alright. what are you running for spark plugs? and at what gap?

 

I'm going to assume you have converted to a return type fuel system?



What is your idle A/F?



Cruise A/F?



Acceleration with no boost A/F?