I know this question has been asked a 1000+ times

[coupe00]

What is the best lowering spring that is still good for drag launches but still has good ride quality?

[SexOnWheels]

The Strano Springs are supposed to be good for drag and road racing:

His company website is here: http://www.stranoparts.com/

And here is a few threads pertaining to members experience with them.

http://www.ls1tech.com/forums/showthread.php?t=644012

http://www.ls1tech.com/forums/showthread.php?t=576054