That is EXACTLY what happens. Same as the fuel chemists.
When you see the same kart 3 times before the first heat race -- you know something's up.
This is particularly true with the baby champs (Subaru engine with governor) and Predator classes using a governor.
I have not seen it played out in the LO206 the same since their rev limiter is digital (ie in the coil) rather than mechanical with the governor, but tech men still need to check them with YOUR OWN tach - trust me, I've seen plenty of differences in tachs. Some, I am convinced were meddled with.
My veteran ears can still tell the difference of 5000 rpm and 5500 rpm.
Yea, where is Mychron Mike (or Devan, or whomever) these days. Their input would be much appreciated.