My belief is you should stick with a system.  If you're looking to lower the vehicle, stick with Steeda components.  I'm sure they've tested things together, rather than just putting out a larger swaybar (bigger isn't always better).  For myself, I know the amount of engineering that various Mfgs put into police packages- it's an important market and those vehicles get tested extensively.  For that reason, I'd roll with the PIU (police) shocks and swaybars- they use the same springs as the ST.
Of course, handling is subjective- you could "try" the steeda package with the PIU shocks.  Who knows?