...what twisties are you referring to? There's a few industrial parks that wind around, but I can't think of too many places that would offer the chance for a moderately better handling car to run away from you around here (Aurora and Montgomery area).
I've got Eibach springs, new OEM struts, Whiteline rear sway bar, and Perrin endlinks and am very happy with the way the car handles. My roommate can't believe the way it sticks to onramps, even on the Blizzaks... Can't wait for warm weather and the chance to throw the Kuhmo MX's back on the car.
The best handling mod, is of course driver training and being familiar with your car in those situations.