I was thinking same thing.

 

Another question. When spring kits are rated, are the max lift ratings pretty conservative? Because if you do the math, the distance left in the spring before coil bind with the added .050" insurance is always more than the rated max lift from the manufacturer. Taking the example from the first post, the PRC 0.650" max lift springs:

(1.810" Installed Height) - (1.080" Coil Bind) = 0.730"
(0.730") - (0.050" safety net) = 0.680" max lift

So am I doing the math wrong or do they just rate them on the conservative side?

 

I just checked the BTR .660" springs and they seem to be rated correctly with the .050" cushion factor.

1.780 installed height - 1.070 coil bind - 0.050" = 0.660"