I just got my entire Rallye instrument/gauge cluster done by Redline Gauge Works in Newhall, CA. They upgraded my restored/original Rallye tach, but they don't use RT Eng (or anyone else's) "tach board". I won't say what exactly they do (you can call Shannon at Redline and ask him), but the results are superb!!. I picked up my cluster yesterday, and Shannon demonstrated their bench testing/calibration process. Every gauge and instrument performed flawlessly! Shannon and his team are first class technicians. I highly recommend their work.