Change efi or change intakes????

I originally bought the ez with the port conversion kit. finally got the engine together (408" 550hp)and started only to find it wouldn't run/learn under 11".I bought the system before the cam specs (bad idea),I'm using a port matched super victor and converted to sportsman xfi. Its much more tuneable and the only hardware change was the ecu and harness. the sensors stayed. I did have to lock out the distributor and install a phase able rotor. the single plane works better with port injection, when I talked to the FAST guys when they were at Englishtown, they told me the TBI unit was specifically designed around bolt on conversions and dual plane runner designs were figured in to the fuel mapping, but single planes were ideal.