Just to muddy the waters further...this is why I like to master as a separate process. SONAR has enough internal headroom that you can get away with just about anything...just make sure the output is a rational amount below 0 so there's some headroom.
Then when you master, you add dynamics, EQ, etc. and aim for a specific LUFS value. SONAR's Adaptive Limiter lets you see this as well if you want to master within SONAR. The "You Mix, We Master" articles in the Tech+Music eZine address this topic from time to time.