Ford racing P springs compared to stock brembo/track pack springs?

Brembo springs are 131(f) / 167(r).

Eibach Pro Kit is 159 / 193. I'm 99.9% sure the Pro Kit is the same as M-5300-P.

Subjectively, I think the P springs ride better than the Brembo springs do. My stock '12 Brembo GT seemed a lot stiffer than my uncle's '11 GT with P springs and Koni STR.Ts.

That makes sense of course, the stiffer spring goes on the heavy end.

It always seemed strange that most S197 spring rates indicate a stiffer spring on the rear.