they all have sway bars.
how they handle is a careful balance between roll and under-over steer. this also depends on the relative stiffness of the sway bars front versus rear.
in general: the stiffer (THICKER ) the bar, the less roll in corners and better handling. however, if the front is too stiff relative to rear (almost all e46 have this problem, including m3), the car will understeer.
the set up on the perf pack is the most instructive: i think this is the perfect balance for an e46. if you look at m3 in comparison, bars are thicker, but front more than rear. dinan set up, which has a relatively softer nose, returns m3 to perfection.