The British squad has been working on the aerodynamic performance upgrade since last year, before opting to delay its rollout until the 2024 season.
Following a successful test last week, the team has confirmed that it plans to fit the new component to its cars for next week's asphalt rally. Drivers Adrien Fourmaux and Gregoire Munster each chalked up more than 250km of running during their pre-event test days.
"Our plan is to introduce it in Croatia. Everything has gone okay with that, to be honest, and that was always the kind of date we were trying to aim for," M-Sport team principal Richard Millener told Autosport.
"It [the rear wing] is not suddenly going to make us 10 seconds a kilometre faster. There are only small things you can do, and it is small tweaks that we are looking for at the moment.
"This should help us in the higher speed stuff and combined with a couple of other set up changes, it can make a difference to the car. It is constant development, we are a little bit later than the other teams on the rear wing, but we are trying to stay as close as we can to the opposition."
M-Sport has enjoyed a strong start to the 2024 campaign highlighted by back-to-back podium finishes in Sweden and Kenya for Fourmaux, who is sitting third in the championship after three rounds.
Team-mate Munster has picked up three points after a difficult start to the season that included a minor off in Monte Carlo, a puncture in Sweden and broken suspension in Kenya.
Reflecting on the start of the season, Millener is proud of the team's efforts thus far which have outlined the strength of the Puma Rally1.
"I think it is just underlining what we have said last year about the car being okay is being shown here," Millener added.
"We have had a slightly different approach this year we have less expectation. We have Adrien in a strong place mentally and physically and approach the rallies as he needs to with the goal of collecting as many points as possible. Consistency is going to be key for us to do well and I think that has been shown.
"We have had very good reliability touch wood up until now and we have to try and continue that in Croatia. We can be very happy."
