And Waller is wary of the threat former team-mate Stephen Myler will pose for the newly-promoted team.
Myler, who played more than 300 games for Saints between 2006 and 2018, is set to line up for an Irish side who no longer have the threat of relegation looming over them.
Saracens will be the team going down at the end of the season after being punished for salary cap breaches.
And Waller said: "A lot of teams will change their attitude now Saracens are going to be relegated because there's that freedom to play.
"There's no threat of relegation and having to fight it out. It's very much a ringfenced league this year.
"If you look at their team and they've got some fantastic players and real experience.
"We've spoken about Stevie (Myler) and his kicking is a real threat. He can nudge them over from anywhere.
"There's quite a strong Northampton contingent that play there, with Tom Stephenson and Danny Hobbs-Awoyemi as well.
"I haven't spoken to Stevie this week yet but I'm looking forward to playing against him.
"It's always nice when you see your mates.
"He's doing well at Irish and I'm looking forward to seeing the old boy. We'll catch up afterwards, but there will be no love lost on the pitch, I'm sure."