Wait a second, why would the single make less torque?
I don't think everyone here understands why a turbocharger that can move more lbs/min of air more efficiently makes more power....
In order for the power to go up, the torque has to go up or shift positions. In the perfect scenario, going to this bigger turbo will make MORE torque and it will be farther to the right. (right being max RPM of the motor)
If we "maxed" out a turbo that flows more air than the RB's, then it would have to make more torque, assuming everything was good on the tuning and hardware ends.