I get a little cam surge around 1200rpms but not much for your m6 it might have a little more. to be honest you only notice it when your going super slow threw parking lots. your idle will have to be set pretty high like 900rpms when I didnt have my tune done I had to sit at red lights in neutral reving or my car would die. but other than that its a sweet cam. get a tune and it will alomst drive like stock, almost.