Torque and HP are totally related to one another. In the case of the Cummins motor, it generates more horsepower earlier (lower RPM), but it runs out of breathe at the top end (due to engineering choices in the Cummins ISB motor). This is where the Super Duty and Duramax have the advantage. So yeah, you can have more torque, by that you probably produce more power during that part of the RPM band in which you're producing more torque, but the powerstroke and duramax produce more torque higher in the RPM band hence producing more horsepower up there as well. Look at a dyno graph.
