I haven looked at one of there catologes for a couple of years but if I remember right---QA 1 had about the best presentation in there about springs and shocks---mounting angle, rates relative to arm length, unsprung weight,etc

of course when I did my first pro stocker, had problems---but when checking the springs themselves they were all over the place ---ended up with a pair of evry type of spring---probably still have 30 or so of them------