Cook comes in at full back as Jonny May moves to the right wing with Charlie Sharples and Shane Monahan both sidelined.
Freddie Burns returns at fly half and, to accommodate him, Billy Twelvetrees moves across to inside centre.
Darren Dawidiuk gets the nod at hooker and Tom Savage moves into the second row from the blind side flank with Tongan international Kalamafoni taking over the number six shirt.
As Gloucester return to Kingsholm for the first time since the opening day of the season, Davies feels that his side have developed over the past couple of weeks.
"We've learned a lot about ourselves, we've been able to progress and have had three competitive fixtures now. That's where you really test yourselves.
"We've learned a lot. I believe we've got a clear understanding of where our game needs to be and what it's about and, if we can get anywhere near it, then we're going to play a good brand of rugby come Saturday."
Wasps had a good win last weekend and will come to Kingsholm with a spring in their step but Davies knows that every week brings a new challenge for his team:
"We know the size of the challenge and there are never any easy games in the Aviva Premiership, that's for sure.
"Wasps play a particular way and it's really challenging every week to come in and look at the respective styles of play of the teams that we're coming up against.
"But our focus is absolutely on ourselves and getting our own game right but with a slight variation depending on who we're playing. It's heads on this Saturday making sure we put in the performance and get the result."
Rob Cook; Jonny May, Henry Trinder, Billy Twelvetrees, James Simpson-Daniel; Freddie Burns, Dan Robson; Nick Wood, Darren Dawidiuk, Rupert Harden; Tom Savage, Jim Hamilton (capt); Sione Kalamafoni, Andy Hazell, Ben Morgan
Huia Edmonds, Dan Murphy, Shaun Knight, Will James, Akapusi Qera, Dave Lewis, Mike Tindall, Martyn Thomas