Corvette suspension users,
I posted a question in the past about this and have learned quite a bit since. I can't be sure I added it correctly but the link is below.
Anyway, I'm using a narrowed C4 suspension and had some issues with stiffness and wear. I found that Vette Brakes was not only local but Gary and his team are as professional as I've seen. They custom make everything in house. 
I recently installed their entire tubular system to include trailing arms, camber smart struts and toe bars as well as a new narrowed leaf. This leads me to my question. What rate spring do you have in your car?
My TRW spring was measured at 681 lbs. Factory Corvette is closer to 300-400 lbs. They shortened a softer rate one for me and it's still 517 lbs. I also understand that Everett Morrison ordered 500 lb springs for their cars.
Anyone have any ideas as to what a good rate would be for a Cobra?
Mike 
http://clubcobra.com/forums/showthread.php?t=107568