https://www.bmwusa.com/vehicles/m-models/m2-coupe/overview.html
Yes, inline 6, twin turbo, 473hp. Its a completely different engine from the 2.5 Mazda turbo engine. For one, Mazda's 2.5 turbo is a 4-cylinder... Also, Mazda doesn't go for big horsepower numbers, like BMW's M cars.