Just been reading about the replacement for 2016 M6 GT3 same 4.4 V8 but 585 hp so if it sounds as brutal as the Z4 bound to be a winner.
http://www.bmw-motorsport.com/en/cars/bmw-m6-gt3.html
http://www.bmw-motorsport.com/en/cars/bmw-m6-gt3.html