This is a good thread:
Bottom line, I wouldn't do it and not only because you have to replace parts. The M3 has a different braking system entirely (different master cylinder) ... who knows what kind of effect that will have on braking performance.
2011 BMW E92 335i, 6MT, Le Mans blue - Quaife LSD, JRZ RS Pro, JRZ camber plates, Eibach ERS, full M3 susp, custom toe arms, Powergrid end-links, SS brake lines, brake ducting, Michelin PSS, UUC SSK, ETS FMIC, ER CP, Perf. Exhaust, VAC RSIK, Sparcos; work by VAC Motorsports in Philadelphia