[wilf leek]

IF, as I suspect, the MSD limiter chip is actually just a resistor (different resistance for different rpm limits) then I would expect it at best to be +/- 1%. Tolerance bands on resistors can be +/-10% or better, only high-precision items approach the 1% mark.

That being the case (any elctronics experts to say yay or nay?), then the actual rpms that the thing cuts in (out) at would also vary within that tolerance band.

Plus of course, I view most tachos with the same degree of scepticism as to it's accuracy as I do all other automotive guages.