Get the springs off the rear drive M sport. There will be plenty available here for cheap because so many people swap out suspension. For the cost you wont beat it. If you want more I would go KW or another fully adjustable system. PM some vendors and they will be able to give you the best answer.
2010 AW e90 328i: 6 speed, Black Leather, Dark Wood trim, ZPP, ZCW, ZVP,ZSP, Nav, Xenon
BMW Performance CF Rear spolier and Gloss black grills
2008 Candy White MKV GTI 2.0T 6 Speed Manul Gone
2008 AW X3 3.0si: 6 speed Returned
2006 AW e90 330i: 6 speed Dinan Stage 1 Returned