Usually, if they are Ford springs, they will have a green tag on them with the spring rate in black. It might not be there though due to weather
I like Eibach for sport springs. If you lower you car, make sure you get caster/camber plates. You probably already know that, but you'll be suprised how many ppl don't know that. I am currently running Eibach's Sprot Springs with a 2" drop. I really like how it handles and the agressive look it gave my stang. I am redoing my suspension so thoses are going bye-bye
I am installing drag springs here in a few weeks.