[IMO]Asking for opinions here is like trying to get a drink from a firehose!
The full-tilt Ground Controls require welding and fab skills to install. In addition the cost is only justified for all-out competition or for those with money to burn. Added benefit is more camber adjustment.
Short of all out, the $400 Ground Control kit is a really good deal. It's a bolt on and you can choose your spring (Eibach) rates. If you encounter rough pavement or bad streets, anything over 250-300# fronts will ride like a sled and play hell with your upper strut mounts. However they can be a very good rattle and squeak locating device.
Don't forget the rear geometry requires a stiffer spring on the rear than the actual wheel rate you want. Spring rate X .65 = wheel rate. Or a 450 #spring X .65 = Wheel rate of 292#. Common sense and experience says the front of a sedan should be stiffer than the rear.
st600r loves it for a track car - see previous post.
A good low cost setup for a track car would be the $400 kit with the Ground Control camber adjusters for $300.
$700 total - with no shocks.[/IMO] That tag is my contribution to html.
http://www.ground-control-store.com/products/category.php/CA=98http://www.ground-control-store.com/products/description.php/II=142/CA=8
