Put together a quick comparison between clutch modifications for those trying to understand the difference. The higher the belt comes up out of the secondary clutch, the lower the take off gear ratio. This yields greater starting torque transfer, something that generally wanted by everyone. This has nothing to do with your top speed, however your speed may be influenced depending on the modification used to get the belt to the height achieved. Stiffer secondary springs help you stay in this low ratio longer, but do not actually change your ratio. Therefore ratio must be changed through modification of the cvt system.
The first two images show belt exposure with the cvt cover in place. As you can see the Hunterworks runs at the absolute maximum belt height, just slightly below the cover (He actually uses feeler gauges to determine belt height). The more you machine the sheave, the more low end you can achieve. The bottom line; you cannot achieve lower gearing without damaging either your belt or your cvt cover. Anyone can grind metal out, proper tuning of the cvt system is key here.
Lastly is my sheave which is a highly modified version of the Hunterworks sheave, fixed sheave and secondary. Many of dunes/rock crawler drivers do not use their cvt covers in order to keep their cvt belt temperatures low and to maximize their sheave modifications well beyond the norm.
My current clutch setup lowers the cvt gear ratio 48% lower than stock. For some reference, the Hunterworks clutch is 24% lower for the rhinos and 16% lower on the Wolverines, mainly due to the cvt cover limitations. At a reduction of 48%, I have the ability to use 31" tires and still have the gear reduction of 24% over stock. I think 27's will suffice for now and I can climb up anything in high gear while still maxing out at 56mph.
For my rock crawling, the slower the better. Horsepower sells cars, but it's torque that wins races.
Here's some interesting reading about clutch mods pre- 2010 and who originally created them.
Nyroc's ATV info website
Link for purchasing shims: Rhino Shim Mod on Ebay
The Tinken/Camshaw X-Clutch, an experimental leap into the future of high performance clutches. The combination of next level sheave machining combined yields 12mm of belt exposure out of the secondary clutch makes for some massive low end power. It's these advances in research and development which further the performance of available aftermarket clutch systems.