What the rationale is for the 4400 rpm limit I don't know but given the rest of the ECU's sophistication I'm sure it's not arbitrary. Maybe the existing software isn't effective enough above that level. Maybe the OEM schedules were set most aggressive at part power to ensure the best gas mileage but higher power operation was designed with more margin such that the OEM knock system really wouldn't challenge the knock limit at high power. I'm really just speculating here. Gotta go back over to General and rattle some tuner's chains! Stand by.