Eibach's are junk and will sag after a year. You have to decide what you want to achieve.. Looks? Handling? Both?
Handling and Looks dept i would go with the Tein's or Mazdaspeed with the rear camber. Cant go wrong there.
i heard good things about the road magnets for the street but dont know about the track.
had the eibachs on my stang for 4 years and they felt like stock springs. I guess youve experienced different.
Seeing as ive owned 18 mustangs, 5 of them Cobras, i tried Eibachs on just about all of them, always ditching them for H&R or coilovers. I didnt learn until my last car to goto H&R from the get go.
Do any of the spings mentioned require a shock upgrade as well?
i really like how cobb staggered their spring tensions. one of our biggest problems is putting power down in the front wheels, obviously, and outside of changing our tires, staggering suspension stiffness is the only other way i can think of that will net appreciable gains in this department.