I don't have track times to compare before and after times, but the car defenitely feels more agile in cornering. The stock suspension is actually really impressive, but these springs make it easier to change directions when cornering at the limit without losing the back end. The drop at the front is 1.625 inches, and the drop at the back is 0.75 inches. I recently drove to and from South Florida from Atlanta with a ton of luggage (both trunk and back seats completely filled) and there was never any rubbing.
I'm not sure if these links will work but here's a before (1st pic) and after pic.
http://photo-origin.tickle.com/image/91/1/2/O/91123155O614474015.jpg
http://photo-origin.tickle.com/image/91/1/2/O/91122647O641879182.jpg
Unfortunately in the second pic the car is on a slope and the pic is taken from the high side the drop can't be appreciated as much. If I can find a better one I'll post it up.
Edit: If you're looking for springs that slam the car these aren't the ones to get. But the ride quality is great as is the handling