Originally Posted by HP Autowerks
Front can range from 350 to 450, with 450 is the absolute max for TCKR front DA's. We have done more installs than any other TCKR dealer and have competed in Redline Time Attack in our own 335i and sponsored the only podium finish E9x M3 in stock RWD class. Anything above 450 you will likely to fun the rebound setting maxed out or require revalving. Rear can be 600 to 800, with 800 being max.
The best street and light track combo would be 350 or 400 front with 650-700 rear.
I'm surprised the DA damper can handle a F spring rate of only 450 lbf/in max! I was running their SA setup with 400/672 rates, and the SA damper/strut had no trouble handling a F rate of 400 - I thought the DA kit could handle a wider range of rates than the SA kit?