If you do some research you will find that the performance with lowering springs and stock shocks will worsen the lower you go. The ride height on the car in the link was achieved with coil-overs and I would bet that the ride quality will suck if you tried to go that low with the spring-over kit. Even with coilovers that ride-height is very impractical. I had mine set almost that low and I was scraping often. It looks cool but it takes away from the driving experience.
'08 E90 M3 - Alpine White - Sold
'13 E92 M3 - Silverstone II - Sold
'04 E46 M3 - Jet Black - BBS E88, KW Clubsports, Brembo BBK, SuperSprint Exhaust