I have an S54 Z3M that was remapped at Evolve on their Dyno years ago, no mods at all. They told me it was the first Z3M map they had written.
The difference was night and day, midrange was improved and the torque from low revs is great.
325bhp to 349bhp so not massive gains on power but the car drove really nice after.
I’d say go for it if it’s done on the dyno.