Originally Posted by sosidge

Extra yellows are harder, about HPI silver/Tamiya Blue equivalent. Extra Reds are soft, about old Tamiya Red equivalent. Kit Blacks are medium, about old Tamiya Red equivalent.

You will probably need to run another manufacturers springs to get the fine differences between rates that most people are looking for. Seems the team drivers are mostly setting the car up with Yokomo or HPI springs. I've got ARC springs to hand.