The M:B:T musical grid is the fixed visual reference in SONAR rather than absolute time. So when you change the tempo, audio clips will appear to change length, but their absolute playback timing won't change.
If you're trying to fit the project tempo to imported audio, try using Set Measure/Beat At Now to tell SONAR where the measure lines should fall. If the tempo is fixed, and the audio starts on a downbeat, you may only need to count out 8 measures, and set 9:01 to get a reasonable fit.