A lot of people seem to like the FMS "C" springs. They give a good drop and ride pretty nice. Other good options are Steeda Sport springs, Eibachs, or H&R's.
I thought the "C" springs rode a little rougher than the "B" springs? "B" springs are what I am looking at one day because they won't jar your kidney's as bad. I could be talking outa my hat though. Just going from what I have read in the past. Anyone else?