The hard up shift is very nice as it is an instant rpm jump and instant trackspeed. Use the green spring if this is what you want to accomplish, great for boondocking where instant power is needed.
From what I've found: Stiff second spring limits your trackspeed while climing. It deosn't allow the motor to load and use the hp. With the stiff spring in my sled, I instantly hit 32 mph track speed (deep powder pull) and it runs 32 mph without increase or decrease. The rpm hold steady and the power feels flat.
I've ridden other sleds with similar motor mods, and softer springs/less weight in primary and they seem to pull hard while climbing at peak rpm, when the track hits a deep spot, or crosses another trench, the rpm pull down and then regain. I feel that the motor is being loaded and the hp is being used.
I use a 38/34 rkt helix as well and load the primary with 71 grams of weight at 7-10k elev, and am going to try the red cat spring this season.
