The Black/Orange is a spring that was based on the characteristics requested by owners and tuners of the Sidewinder turbo model. Spring 2017 initial tests on the prototype springs showed that when installed it ran similar RPM to the stock secondary spring, but that the more initial side pressure showed some desired characteristics of quicker RPM and better belt grip on initial take off.
 
Some Sidewinder customers have requested a heavier spring for testing certain applications of very tall gearing or higher load conditions. We have a new option for those interested - the Black-Tan.