Do a turbo delete mod. That'll make it louder!
I can't say anything about the unburnt fuel, but noise is a form of energy. An engine that runs quieter is using more of the energy from the fuel and will theoretically make more power. That doesn't mean running a muffler or a quieter exhaust in general will make your truck more powerful, because that is just converting the energy into another form. That said, I don't agree with anything coco said.
I didn't mean exhaust noise specifically, like a quieter or louder exhaust, I meant excessive undue noise you hear through the exhaust pulse/note, that then can be followed back to the engine and hear in the form of the engine moving/working.
You don't agree with anything I said, huh? Yet you encompassed pretty much all of it. Really its too big a principle for ME to try and explain, I can't remember or find the site I read about this, but you hit the nail on the head.
Noise is a form of energy, so is heat. Noisy engines, are less efficient. Period. Take the powerstroke for example, it claks like no other, yet it's not all that powerful and even a stock one will smoke(unburnt fuel due to inefficiency) same thing for mid to early 2000's dodges, yet they make good power, the duramax on the other hand, is one of the quietest v8 diesels I have ever heard, and the cleanest burning out of the big three, even tuned with an exhaust it's quieter than my buddies stock dodge, well, he does have an exhaust now, but stock to stock, we all know the duramax is a quieter running machine, and, cubic inch to cubic inch, the d-max puts out more power, and I'd be willing to bet, less heat out the tailpipe too.
I apologize for making this point out of context with the op's thread, what I was trying to get across was not what the op was asking for/about. However what i was saying, was in fact, truth. Wether or not you want to understand it, or agree with me, well, that doesn't really matter to me...