With IR EFI, you're pretty much stuck with speed density control scheme, no MAF (mass air flow) unless you want to put those pretty stacks inside and air box. Manifold Absolute Pressure through common plenum with EFI is sensitive to both the communication port size to each runner and plenum size. There can be a bit of trial and error if not voodoo here as you're really using MAP as a predictor of engine load for corresponding enrichment schemes.
Interestingly, in carbureted IR systems, this scheme can dampen reversion pulses and help smooth out eratic idle and off idle transition problems.
Best,
Kelly