Originally Posted by HP Autowerks
400F and 800R is more ideal. The extra low rear rate is great for the ride quality and traction, but the vehicle will understeer and you can never get the backend to rotate as much as you would like it to.
It would be the 9" Swift for the back of the E9x.
We like to use the higher quality Swift springs along with thrust sheets.
A photo below with Swift springs, thrust sheets, and the more robust height adjusters.
Its time for me to go the same route. Its good you tried the swift setup, as we discussed months ago before I bought the Ohlins kit. those spring rates are ridiculous ;]