kevin lluevano swears by his rear strut tower brace - I love my Steeda "Rear Sway bar" aka Torsion Beam Brace - I don't have a rear sway yet but this made the back end feel so much better behaved.
so to recap here is my setup
ST Suspensions XTA Adjustable Coilovers
XXR 521 17x7 ET38
Hankook Ventus 215-45-17
Pierce Motorsports Front Strut Tower Brace
Pierce Motorsports Front Tie Brace
Steeda "Rear Sway Bar"
COBB RMM (this is a key cornering control piece IMO)
so to recap here is my setup
ST Suspensions XTA Adjustable Coilovers
XXR 521 17x7 ET38
Hankook Ventus 215-45-17
Pierce Motorsports Front Strut Tower Brace
Pierce Motorsports Front Tie Brace
Steeda "Rear Sway Bar"
COBB RMM (this is a key cornering control piece IMO)
Also, for street driving on twisty roads, having too stiff of a setup may not be good.. a little flex could help rotate the rear end better..
The FiST is really good on the rear side, and if anything that needs improvement, it would be the front 2 wheels as they carry most of the load during cornering and hard braking.. IMO, just the front strut brace and the lower front tie bar is more than enough for spirited street driving..