99 L29 7.4 with 0411 PCM. Idle loggign shows 850 RPM and the tach is like 1200, 1450 log is 2000 tach and then it gradually raises a bit from there. I searched and found some people doing other tachs and playing with the tach output to get some changes but I tried several variations of the same number to mixed numbers and it didn't change at all. I've tried a 99 V8 gauge cluster, 98 and 96 all with similar results.