i personally think the m6 is already beautiful, all it needs are rims, lowering and meisterschaft exhaust and you are set. however, if you feel the need to be unique, thats cool too, it would be something i would do personally. attached are pictures of the hamann front lip and the lumma clr600 bodykit, alot of people dont like it but i think it looks cool. also the wheels of my choice would be the vr2 and vr7 vipmodular rims, i ve seen them in person on my friend's bimmers and they look amazing, plus you ll be unique since everyone else has iforged or dpes.
just my opinion though.