I'm the buddy of AMG running the Fantom springs.
Front:-- green front tyre... 40
Rear:-- red front tyre 37
I was running V-one R gold front and black rear.
Let me tell you I dont quite know why the harder springs are working better..... but they are!
Only changed them over before the last race night... improvement very noticeable!!!!!!
see for your self....
Before spring change.....
20 laps in 5:08:91
Average lap..... 15:44
Best lap..... 14:05
After spring change......
22 laps in 5:12:08
Average lap..... 14:18
Best lap...... 13:34
2 more laps
Average lap dropped by 1.26sec
Best lap dropped by 0.7sec