Testing the HiRev 7500

RustyRatRod said
It depends on the type box and how crappy it is. Some actually have high RPM retard designed it to help protect against detonation at high RPM.

It's clear as mud whether any retard was purposely built into HEI or other units, or this was just some BS marketing people came up with as they struggled to explain what was happening. See that link on Speedtalk I posted earlier the thread.