A guy I work with has an 05 denali pickup. He claims it was 390hp stock and with his super chip programer he guess' its around 410hp. Its very sexy and very quick, it out runs my boss's 07 duramax with the power programer set on 4 ( sorry I dont know what programer or "chip" the duamax has but it has 6 settings 0-5 0 being stock) the duamax set on 5 however literaly leaves the denali in its smoke.
I do know GMC's web site claims 416hp stock for the 07-08 denali's BUT it also says its now a 6.2l gas V8, rather than a 6.0