I just installed some on my 325xiT form ACS, they are made for the car. They are manufactured by Eibach for ACS. They are still progressive, but are a little softer intially, but they really come on strong once they are loaded in a corner. I think they are even better than stock on rough sections, and much better in the corners. Lowering looks spot on to me, very level with very littel gap. Bought them from CES. A little less than $400.00 with shipping. Dealer installed, so I know there are no issues.
325xiT, Manual, Titanium Silver, Black with Alum Interior, Premium Package, Sport Package, Winter Package, Xenon Adaptive Headlights, 18" 196 Wheels, ACS Springs, Tinted Windows, Chrome tips, UUC Shadow Shift knob, BMW Alum Pedal set, BMW strut brace