The Steeda springs will work very well. The SR springs AM sells are actually good too and so are the BBKs I had on my last car. Actually those BBK springs and Tokico shocks rode damn near as smooth as stock and the car was dropped about an inch at all 4 corners.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.