Swaybar vs. lowering springs

[kelevra]

Some interesting info in this thread.
I'm looking to keep the power stock, but upgrade the handling as I enjoy the light weight of the car and throwing it into turns. I'm an ex sport bike racer so I'm pretty smooth with the controls (not bragging, just saying). I'd like to add the rear sway, springs, shocks and grippier tires, preferable all at once.

Please tell me what differences I might feel if I went with the TRD 19mm or the other brand with the 23mm? Springs that improve the handling but don't wreck the day to day driving experience? Same with the shocks. I'd like to get some nice aftermarket rims, but don't want to go much bigger then stock as I want to keep the ride relatively nice.
I don't plan on doing any autocross events, I just want the handling to improve sharply for when I get the itch. Basically, when the weather is nice I ride my CBR1000RR, but it would be nice after 2 years of owning this yaris hatch, to get the suspension in higher tune. Thanks for all replys.