This looks interesting. A spring that's not as stiff yet improve the feel over stock. It's 35 lb/in instead of 185 lb/in for the S550 cars. Has anyone tried it yet?
http://www.steeda.com/steeda-s550-mustang-clutch-spring-assist-35-lb-in-15-16-all-555-7022/
http://www.steeda.com/steeda-s550-mustang-clutch-spring-assist-35-lb-in-15-16-all-555-7022/