I can't say much about the rears, but the fronts I have (and don't use anymore) are linear. I measured them (with a scale and a press) at 443 +/- 7 lb/in, ie one was 436 and one was 450 lb/in. My notes say the rears were 180lb/in, but that's probably wrong. The rears, as I recall, are also linear, and probably in the low 200s. The fronts should be matched with rears somewhere around 275 to 300lb/in if you don't want to look like a ricer.
They lowered the car too much for me, since I was aiming for the lower arms to be parallel to the ground. Without the spacer I put in, they probably lowered it 2" from stock.
TRD may have changed their design from when I bought them 10+ years ago.
Asterix