Maguire started in the center of a back three for recently hired head coach Amorim at the Etihad Stadium on Sunday.
United won the game 2-1, with Amad Diallo winning a penalty that Bruno Fernandes converted before he slotted home the winner minutes later.
"We had chances, we pushed in the end and got the reward I felt like we deserved," Maguire stated post-game.
"It was a great performance to go there, have 50-50 of the ball and have the same amount of shots as them.
"It's not been like that in recent years, so it's an improvement, but there's still a long way to go. Winning football matches is really important. When you play for this club, it demands winning.
"Obviously, we had back-to-back defeats in the Premier League, so to go there and put a statement down is really important for our confidence and the belief of where we're going, and where Ruben’s going to take us.
"Like I said, I'm sure it's going to be a positive journey."