DD15 HP ratings

Please forgive my ignorance, but I’ve searched the forum and have been unable to find an answer, and you can’t learn without asking questions. Can someone please explain to me how the DD15 hp rating works? Why do you always see trucks for sale listed at 455 hp but looking around on the forums here, I’ve read that all the engine covers say 560 hp? The DD15 brochure has a chart with the different hp ratings on it.

Why is this? Aren’t all DD15s the same? There’s nothing to differentiate between them. Aren’t they all the same displacement, same bore, same stroke? What creates the differences in the hp rating? Is it just the ECM? Can all DD15s handle 560hp without changing any hard parts?

Here’s a hypothetical. Say I have a DD15 rated at 455 hp. What do I need to do to get it to 560 hp, just get the ECM files changed if it doesn’t require any hard part upgrades?Let’s also look at the inverse, say I have a 560 hp and want it turned down for whatever reason, maybe I’m hiring a driver or something. If it is just the file in the ECM, does it go both ways, it can be turned up or down, or would hard parts need to be changed either direction?

If you’ve made it this far, you’re probably now just as confused as I am, but it’s something I’ve been curious about for a while now. Any input would be appreciated!

 

Thank you for your response! I apologize for using the incorrect nomenclature, but now that I know what it’s referred to as, that will probably help to narrow any further searches I make about this.

Since those are options that are selected at ordering, is it possible to change them later? Who can do that sort of thing? If I own the truck, can I just whip into a Freightliner shop and have them change the configurations, or is it more specialized?