Well, realoem does list different struts on four corners, and an additional rear roll bar, for the 2010 35d. The struts are around $1000 per axle, the anti-roll bar is a few hundred, and the springs aren't listed, but guess at 1200 or so. $3500 in parts, plus labour, seems expensive to me. I'd put the same money towards AD on my next purchase.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue