3" drop is a LOT. Didn't even know you could go that low. Realize how much an extreme drop is going to compromise the driveability of your car - getting into driveways, speed bumps ... and it will especially suck in the winter. I would go for 1" front and rear to start, then lower as needed. 1" drop looks good on these cars.
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