[David Pozzi]

I Found my notes.
coil rates are rounded off.

A 300 coil on a 21st century sub has a wheel rate of 156.
A 350 coil = 182
A 400 coil = 208
A 450 coil = 234

A 650 coil on a stock sub has a wheel rate of 156.
A 750 coil = 182
A 850 coil = 208
A 950 coil = 234
You will notice a 50 lb increase in 21st centruy sub = a 100 lb increase in the stock sub.

On a 21'st Century sub, multiply coil rate by .521 = Wheel Rate

Bad Penny started out at 350 went to 450 to 475 for quite a while and I think may have ended up around 500-550.
Steve always wanted to run the car super low, so we had somewhat limited bump travel. We had to go stiffer to make it work. With a higher ride height and more travel, you can run a softer spring. Shocks have a huge influence in this too.