When comparing dyno charts, one must be very careful on issues of calibrations and scaling. Using the later Dynojets with built-in tamper-proof weather-stations, one can be assured of proper corrections. However, even with mis-calibrated dynos, you probably won't see more than a 10% variation anyway. In most of the charts below, there are dramatic differences, so the calibration issue would yield insignificant change.
The other issue with comparing charts
between different runs, different cars, from different dynos (aside
from calibration issue above), the is correct scaling and super-imposing
of the charts. On my overlays below, I made sure that all the
charts were sized to the correct axes with idental scaling (no
0-300 charts on top of 50-200 charts without correction).