Official ratings of new Duramax

[KCJackson]

From the GM press release:

Duramax 6600 Provides Major Improvements In Power, Torque, and Emissions
PONTIAC, MICH. - GM's Duramax 6600 6.6L turbo-diesel V-8 engine will provide higher power and torque ratings and major emission improvements beginning in January 2004.
Silverado and Sierra 2500HD and 3500 Series trucks with the Duramax 6600 and the Allison automatic transmission will receive a new version of the engine with 310 hp @ 3100 rpm, 10 more horsepower than before. The engine also features a higher torque rating of 590 lb-ft @ 1600 rpm, a 70 lb-ft increase over its previous maximum high. At the same time, Duramax 6600 NOx emissions have been reduced almost by half.
"Since its introduction in 2001, the Duramax 6600 has re-established GM in the full-size diesel powered truck market by increasing our share of the segment to nearly 30 percent," said Charlie Freese, executive director, diesel engineering for GM Powertrain.
Silverado and Sierra models with the Duramax 6600 and a standard ZF S6-650 six-speed manual transmission receive the same emissions improvements as those with the Allison 1000, with carryover power ratings.

In a nutshell:

Duramax/Allison: 310@3100/590@1600
Duramax/ZF: 300@3000/520@1800

Powerstroke: 325@3300/560@2000, all transmissions

Cummins: 325@2900/600@1600, all transmissions

The choice is clear