I have used Performance Trends Drag Racing Analyzer v3.2 and also the Engine analyzer. They have produced very good results for both component changes and ET prediction with weather changes. Once you get your combination tuned in by using the match vehicle performance function, it has predicted very closly what different changes will do to your ET and engine RPM. I have used it for checking an 82 mustang as well as a rear engine dragster.
http://performancetrends.com/drag_racing_analyzer.htm