Paul Griffen, a New Zealander who by his own admission came to Italy primarily as a tourist, replaces the injured Alessandro Troncon at scrum-half as he makes his bow for the Azzurri but both Kirwan and Griffen believe Italy can put on a good show.
Kirwan, who also hails from New Zealand, said: "Paul is in great form.
"His decision making and his passing is very good.
"You cannot make a comparison with Troncon - they have different qualities."
The former All Black legend says he has not changed his side to take account the absences of Martin Johnson (retired), Neil Back and Jonny Wilkinson (injured).
"That has not changed our preparation for the game," said Kirwan.
"Without Martin Johnson who is a great leader, we are hoping that England won't take control. Wilkinson guarantees more points when England are under pressure.
"We are hoping those two losses will affect them, although I think the guys who will playing in their place will try and make the best of this opportunity."
Griffen admits that a match with the most powerful team in world rugby has given him some nerves but he is looking forward to the occasion.
Griffen said: "We know England play a structured game - they will be without three key players.
"They will be forced to change the way they play. We will not be worried about what they do as we are focusing on their game.
"We have been working a lot in our defence and I really think we can stop them and try and catch them on the counter-attack."
Referring to the absent trio, Griffen said: "Wilkinson is a freak of rugby, Martin Johnson is a leader and Neil Back is an orchestrator of many of their plays.
"But the players that will replace them may not have the same experience but they certainly have the hunger to do well and establish themselves in the team."
Flanker Andrea De Rossi replaces Troncon as skipper while Benetton Treviso stars Santiago Dellape and Denis Dallan passed their fitness tests on Friday and are in the side.
Kirwan has opted for winger Nicola Mazzucato's experience for Sunday's game with Stade Francais player Mirco Bergamasco relegated to the bench although Andrea Masi will play at full-back, a position the younger Bergamasco brother has also filled in the past.
Bergamasco has been unable to recover fully from a thigh injury picked up in Wednesday's training.
De Rossi admits he is relishing his first match as skipper.
"Every match has its own history and it's own moments," said the flanker.
"This is the most important game in our recent history as we are facing the world champions.
"The motivations will be bigger than in any other game."
De Rossi hopes to gee up some players before battle commences but says others will need to be calmed down.
"Maybe there will be some players who will need to be strongly motivated and others that will need to be calmed down," he said.
With three New Zealand-born players - Rima Wakarua and Aaron Persico join Griffen - three Argentinians and a Romanian, the Italian team continues to have a somewhat multinational feel to it.