It wouldn't hurt to throw them on the M3 when it arrives just to see how they turn out. I agree with the others. They'd look a whole lot better on the M6 with a drop. Keep that in mind for the M3 as wheels always look better without the fender gap.
2013 Mineral White e92 M3 DCT ZCP
2012 Bluefire S1kRR Race ABS QS HG
2008 Sparkling Graphite e90 M3 6spd XXX