Mustang GT (2015) with 421 and 441 hp

Hi there, I have a question. I’ve already been looking for answers on the internet but unfortunately I didn’t find anything. I bought a Ford Mustang GT in December. My Ford Mustang, however, has registered 441 hp and no 421 hp as you know it otherwise. Can anyone tell me why that is so? I’ve seen that there are several Mustangs with 441 hp on mobile but the question is what is the difference here? Is this a special model? A special version? That it’s just more ps I know but I would just like to know exactly what’s behind it. Sounds a bit stupid the question…