Most "lowering" springs actually result in an increase in ride height. If you really want to lower the car, I would suggest you take a look at coilovers. A full set for all four corners would run you about $500.00, but they would allow you to set the height EXACTLY where you want it. They also allow you to choose exactly the spring rate you want, for exactly the ride/performance qualities that you want.
Take a look over at
www.re-speed.com
And here's what my car looks like with them installed (first three clips are of my car). There are not many FBs out there with a lower ride height, and this is how I run it as my daily driver too without any issues (other than having to dodge the occasional road kill):
http://www.youtube.com/watch?v=ZKNjkywj1Q0
.