I dropped 100 lbs. front and rear and will never go back. No change in handling. Got from Summit Racing made by Eibach. Most springs come with a painted on spring rate. Usually as part of part number (ie B2000-350). I tried a 50 lbs. under but that wasn't enough. You can also adjust some shocks for less compression. Visit their web site for how. I have stock and 50 lbs springs for sale if interested. With softer springs you get more body roll in corners, but full travel on most Cobras is 4-5 inches so is 1/2 inch more roll going to kill you?