I've been doing some research myself on this...
Summary:
OEM (Front 1.04 OD x .15 wall 560 lbs @ 1", Rear 0.945 OD x 0.13 wall, 540 lbs @ 1")
Stillen Sway bars $301.78 (Front +21/+48% 1.0625x0.250, Rear +37/+70% 1.0x0.188)
Whitelines Sway Bars? (Front 27mm $271, Rear 24mm $240, End Links $167.70)
Hotchkis $475 (Front 35mm +205% tube, Rear 28.5mm +75% tube)
Eibach (Front 32 (+76%/+117%)or34mm, Rear 29mm (+67%/+98%/+130%))
From the specs I found I think the Stillen and the Eibach are the best. Good stiffness upgrade plus room for tweeking the balance of the car once you determine if you want a little more oversteer or understeer.
Stillen if you want it more streetable
Eibach if you want it more trackable
Whitelines don't have any rate data posted that I've found. If they're solid, that's extra weight.
Hotchkis looks like it'll provide additional understeer. Guess that'd be good for a circle or oval track.
