Suspension help? Which springs?

alright... last thread i posted got nothing...
i have a 91 5.0 coupe
i need new springs... most of my driving is just normal dd duty.. however, i like to have fun around corners and whatnot... i just got new koni shocks and struts all around... but the springs, especially the rear springs... are toast.
what do you guys suggest...
ive heard a lot about frpp c springs...
oh and newb here... what is the difference between progressive and specific rate springs?

thanks a bunch!
-a

i'll look into it... thanks