The SFI may effect idle or could be turned off, not sure how newer cars work but the LT1 is only SFI in idle very low RPM, then batch fire. Just not enough time to fire each injector at higher RPM with cars of this era.

Are newer cars sequential at more then idle RPM? I was told that idle emmisions was only reason for this at time, had no impact on drivability or performace cause there's just not enough time to turn on/off injector for each cylinder.