Anyone else have one of these? Mine works fine but the tach has always read low by 1/8. The stock ignition box read 5K rpm @80MPH (16mph/ 1000rpm). The V&H box reads 5k rpm @70MPH (14mph/1000rpm). The discrepancey is constant across the rpm range.

When I calculate what the correct reading should be, based on gear ratios and tire diameter, the stock box is correct.

Just wondering if my V&H box is engineered wrong or if it is defective, different than other V&H units.