Here's a bit of weirdness.
My 1997 car sat a bit higher at the front than at the rear, so I assumed the springs had sagged. I was given some springs from an earlier (1990) car which measured exactly the specified free lengths and therefore couldn't have sagged. On fitting these the F/R relationship is still the same, and the car isn't even any lower. In fact, the ride heights are pretty much the same all round at 380mm F and around 360mm R (it's a bit lower on the right hand side, presumably because of the battery/steering column/dash weight). Did Mazda use a different subframe and/or top mounts on later NA cars? I would have expected it to sit at about the same height as one of the earlier cars.